To zone UFH or not to zone?

sheff the ref

A great topic to be honest.

I had half made up my mind to go for a Ground Source Heatpump with Underfloor heating, primarily to avoid spending money on oil but a lot of points raised here have put me thinking.

Obviously regardless of the heat source, the concept of underfloor heating is basically maintaining the temperature in a slab of concrete which radiates upwards and heats the house as demanded by the thermostats. That is fair enough and will maintain a constant even level of heat throughout the house.

However a valid point raised is that modern houses with top spec insulation and air tightness will no longer be iceboxes like some of the older houses. Therefore is there really a need to provide a constant even level of heat 24/7. Will a shot of heat through rads at certain intervals do the same job? A matter of personal choice I guess, but rads will not really work effectively with a heatpump so its back to Oil or perhaps pellets which are also going up in price.

Decisions Decisions Decisions

PeteHeat

sheff the ref wrote: »

A great topic to be honest.

I had half made up my mind to go for a Ground Source Heatpump with Underfloor heating, primarily to avoid spending money on oil but a lot of points raised here have put me thinking.

Obviously regardless of the heat source, the concept of underfloor heating is basically maintaining the temperature in a slab of concrete which radiates upwards and heats the house as demanded by the thermostats. That is fair enough and will maintain a constant even level of heat throughout the house.

However a valid point raised is that modern houses with top spec insulation and air tightness will no longer be iceboxes like some of the older houses. Therefore is there really a need to provide a constant even level of heat 24/7. Will a shot of heat through rads at certain intervals do the same job? A matter of personal choice I guess, but rads will not really work effectively with a heatpump so its back to Oil or perhaps pellets which are also going up in price.

Decisions Decisions Decisions

Hi,

You may have read the posts that touch on thermodynamics?

The heat in a very well insulated house will eventually find its way out and the temperature will match the colder temperature outside so it is important to maintain the temperature of the concrete radiator (UFH).

Our electricity prices track the prices of fossil fuels due to the mix of fuel used in our generators similar to the way pellet appears to track oil it doesn't really the problem there is the delivery trucks use diesel.

As you have seen some prefer to allow weather compensating controls to manage the system whereas I prefer step back thermostats inside the house, what we all appear to agree on is no timers on boilers or heat pumps where UFH is concerned.
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Condenser

PeteHeat wrote: »

As you have seen some prefer to allow weather compensating controls to manage the system whereas I prefer step back thermostats inside the house, what we all appear to agree on is no timers on boilers or heat pumps where UFH is concerned.
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Weather compensated controllers also have set backs, set ups and every other control your top end stat could possibly do, plus it monitors the in house temp. In a good system its miles ahead of any stat on the market for comfort and control.

sheff the ref

PeteHeat wrote: »

Hi,

You may have read the posts that touch on thermodynamics?

The heat in a very well insulated house will eventually find its way out and the temperature will match the colder temperature outside so it is important to maintain the temperature of the concrete radiator (UFH).

Our electricity prices track the prices of fossil fuels due to the mix of fuel used in our generators similar to the way pellet appears to track oil it doesn't really the problem there is the delivery trucks use diesel.

As you have seen some prefer to allow weather compensating controls to manage the system whereas I prefer step back thermostats inside the house, what we all appear to agree on is no timers on boilers or heat pumps where UFH is concerned.
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There are a lot of permutations for heating and all forms have their advantages and disadvantages. I am still unsure as to what is the cheapest form of heat though. One thing I am sure of is that there is no such thing as free heat.

JD6910

ya no such thing as free heat and therefore surely a system that you can turn off and on and you want is the bests our new super insulated houses.

i think the geo systems are celtic tiger systems when we all had money to meet the bills and tell the buddies about it down the pub!!!!!

sheff the ref

You could be right. A super insulated house will keep the heat in longer, therefore an injection of heat every so often will remain in the house for longer. Dare I say that oil and rads or wood chip and rads could potentially be the cheapest form of heat for a bungalow less than 2000 square feet.

JD6910 wrote: »

ya no such thing as free heat and therefore surely a system that you can turn off and on and you want is the bests our new super insulated houses.

i think the geo systems are celtic tiger systems when we all had money to meet the bills and tell the buddies about it down the pub!!!!!

PeteHeat

JD6910 wrote: »

ya no such thing as free heat and therefore surely a system that you can turn off and on and you want is the bests our new super insulated houses.

i think the geo systems are celtic tiger systems when we all had money to meet the bills and tell the buddies about it down the pub!!!!!

Sorry I can't agree, if ever heat pumps had a chance of working properly and achieving everything the manufacturer, supplier, installer and home owner hoped for its today not five > ten years ago.

While I don't advertise it heat pumps are part of my business, so why not advertise them?

In the past the biggest problem I had with heat pumps were the customers who appeared to listen but only heard what suited them, I gave up counting the number of sales I let go from 2004 to 2009 because the houses were insulated to 1990's standards.

The final nail in the coffin as far as I was concerned was delivering a system to a customer who had left out a large part of the insulation essentially making the heat pump he had ordered and paid for nothing more than a potential nightmare for both of us.

When I asked why the insulation was left out his reply was he saved €6,500.00 by leaving it out, as I was leaving (with the heat pump) I had to pass by the lads fitting his new really beautiful automated gates that he had spent over €10,000 on, so where were the Celtic Tiger priorities of many?

Today the message about insulation and heating controls appears to have reached most consumers, sadly it took heating oil touching one Euro per litre to deliver that message, a lot of Irish suppliers and installers gave up and moved on some to different technologies others to different countries.

Consumers are looking for the best / most cost efficient way to heat their new super insulated homes, there are obvious suppliers / installers on this this thread we all appear to agree on one thing, the best way to heat those new homes is using low temperature heating systems.

Why? because the houses are now being built to a standard that does not need high temperature systems.

You still have the options of every heating technology, fossil fuels, wood (in its many forms) solar assisted, heat pumps (geo & air) the big difference between today and the Celtic Tiger (pub talking) is you can choose any or a combination of all and the system will work if you get the basics right.
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JD6910

ya we all agree insulation is the key, however it is not cheap therefore we have to ask the question - if i go insane with insulation and future proof the house surely we don't need the constant temp all day everyday. we all live busy lives and even when we are in the house we are running around - therefore surly a stove and standard heating system in our super insulated airtight house is adequate.

i have no doubt the heat pump will work as it should in the super insulated house but do we need the constant temp in the same houses!!!!! also because of the capital cost of insulation surely that combined with high heat pump capital costs - something has to give!!!!

also i understand that the life expectancy of a heat pump is circa 15 years - what happens then??? new heat pump?? i suppose at that stage the technology will have changed and the reality is the homeowner will upgrade to the newer model to maximise efficiency etc...?? a heat pump is circa 10,000 and after 15 years you typically have to replace it therefore it "depreciates" by circa 650 a year - 650 would buy close to a fill of oil or gas!!!!!!!!!!! thats a nice start in keeping your super insulated home warm during the heating season cos you wont need heat over the summer months in the airtight super insulated house.

PeteHeat

JD6910 wrote: »

ya we all agree insulation is the key, however it is not cheap therefore we have to ask the question - if i go insane with insulation and future proof the house surely we don't need the constant temp all day everyday. we all live busy lives and even when we are in the house we are running around - therefore surly a stove and standard heating system in our super insulated airtight house is adequate.

i have no doubt the heat pump will work as it should in the super insulated house but do we need the constant temp in the same houses!!!!! also because of the capital cost of insulation surely that combined with high heat pump capital costs - something has to give!!!!

also i understand that the life expectancy of a heat pump is circa 15 years - what happens then??? new heat pump?? i suppose at that stage the technology will have changed and the reality is the homeowner will upgrade to the newer model to maximise efficiency etc...?? a heat pump is circa 10,000 and after 15 years you typically have to replace it therefore it "depreciates" by circa 650 a year - 650 would buy close to a fill of oil or gas!!!!!!!!!!! thats a nice start in keeping your super insulated home warm during the heating season cos you wont need heat over the summer months in the airtight super insulated house.

Insulation is a one off expense, think of it as the foundation you build from, also probably the one item in every house that has the fastest pay back over any other component.

There are heat pumps in use for over 20 years without any major maintenance, very few if any gas / oil boilers can claim to have that working life.

Maybe it's an age thing but I fail to see the point in working hard all day (sometimes well into the night) and coming home to a cold house.

Leaving the personal preference aside it is easier, quicker and cheaper to bring the temperature back up 2 > 3 c than 5c or more.

You appear to have missed this;

"You still have the options of every heating technology, fossil fuels, wood (in its many forms) solar assisted, heat pumps (geo & air) the big difference between today and the Celtic Tiger (pub talking) is you can choose any or a combination of all and the system will work if you get the basics right."

Nothing stops you using oil, gas, wood gasifier, wood pellet, wood chip, solar efficiently all into a buffer if you can use all of the stored energy, the way to do that is use a low temperature heating system.
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JD6910

can the new high efficiency rads be used for a low temp system???

Ok so the heat pump will last 20 years -that 500 a year!!! What happens after it's life span - refurb it or replace it???? The big differ is an oil or gas boiler is 2K!!!!! That's an easy item to replace every 15 years.

My point is because we are building such insulated houses are the heat pump heating systems required within those homes?

I wonder will the rads be ok with a low temp system??????????

PeteHeat

The radiators should be designed for low temperatures, that way you can a buffer at 80c and by using the proper controls you can reduce the flow to 40c.

A few examples:

Here


Here

Here
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air

Those look really cool Pete, surely quite expensive though?

Condenser

JD6910 wrote: »

can the new high efficiency rads be used for a low temp system???

Ok so the heat pump will last 20 years -that 500 a year!!! What happens after it's life span - refurb it or replace it???? The big differ is an oil or gas boiler is 2K!!!!! That's an easy item to replace every 15 years.

My point is because we are building such insulated houses are the heat pump heating systems required within those homes?

I wonder will the rads be ok with a low temp system??????????

A HP would not cost the same price to replace. Firstly you may get away with only replacing the compressor and drier and doing an oil acidity test. About €1000-1500 would cover this.
In the case of replacing the entire heat pump, you would not be replacing the collector, pipework, divertor valves, expansion vessels, labour involved in initial installation etc. All of this makes up a significant cost in the installation of a heat pump in a new build. So you're depreciation figures are way off.
Jaga rads are the best out there for running at low temp but I would not use rads with a heat pump in a new build. Heat pumps are designed for long periods of running and long periods of downtime. The intermittent requirement for heat from rads do not lend themselves to that fact and only a huge buffer tank would overcome this fact. Use UFH while you have the option. You can use setbacks for when you're not there to let the house cool away slightly and it will take very little time to heat back up just before you arrive back.

Do-more

I'm following a similar discussion on another board about zoning etc. Someone in that discussion says that Honeywell produced research which suggests a 15% saving in running the heating "always on" rather than "on, off" but they haven't provided a link to the study, but you could have a search for it.

I live in Sweden which has a long history of well insulated, well heated houses. Regardless of the heat source used, be it oil (very few left) wood or heat pump or whether they have rads or ufh everyone runs their heating "always on". Swedes are not known for wasting money.

The "on, off" method is purely a way to heat badly insulated houses where the heat losses mean that much of what is spent on heating them ia wasted anyway.

Condenser

Do-more wrote: »

I'm following a similar discussion on another board about zoning etc. Someone in that discussion says that Honeywell produced research which suggests a 15% saving in running the heating "always on" rather than "on, off" but they haven't provided a link to the study, but you could have a search for it.

I live in Sweden which has a long history of well insulated, well heated houses. Regardless of the heat source used, be it oil (very few left) wood or heat pump or whether they have rads or ufh everyone runs their heating "always on". Swedes are not known for wasting money.

The "on, off" method is purely a way to heat badly insulated houses where the heat losses mean that much of what is spent on heating them ia wasted anyway.

Exactly, it takes alot of energy to repeatedly heat the building fabric. Consistent heat, with setback periods if desired and all areas treated equally is by far the most efficient.

JD6910

efficient ...... but at what cost(capitial cost, on-going cost per month and ultimately replace or upgrade cost after the life expectancy of 15 years) and . the point still remains why would you want the house heating kicking in while you are at work.... and yes i know because the house will be warm when u get home - you could still set the heating for 4.30pm for an hour before you return home!!!!!!

air

JD, you've asked questions in this and several other threads over the past few days and you've gotten a lot of very good advice. However you either seem to have not understood any of it or don't want to listen to it so I don't really know why you asked in the first place.
The reason it's no good turning on the heating an hour before you come home is that fast response systems don't make much sense in modern low energy homes.
Half the benefit of a low energy home is that the internal thermal mass never cools down much which makes for a lovely environment. Walls and floors aren't cold to the touch and radiate heat back to you.

Sure, you could install an over sized boiler and high output rads and then blast the house for an hour before coming home. However the internal walls and floors will still be cold (they will take almost as long to heat up as a "normal home" as the thermal mass is going to be similar). On top of that, when you are home for longer periods of time, your over sized boiler is going to be constantly cutting in and out for short periods, making it inefficient and reducing the lifespan of itself and all associated components.

With the greatest of respect, I don't think you have a great grasp of the whole area and I would advise you to take some qualified independent advice. Go with whatever they advise as it is highly likely to perform better than any scheme you are likely to devise yourself.

PeteHeat

air wrote: »

Those look really cool Pete, surely quite expensive though?

Sorry for the delay replying, I don't know the prices today they were expensive a few years ago when I priced them.

Personally I would go with UFH if building new, in fact I will be building new in the next 24 months and I will be using UFH.
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fclauson

soundskin wrote: »

The advantage of weather compensation over s-plan heating controls (timeclock & thermostat) is that is a predictive control for house temperature instead of a reactive control that will will get a standard heating controls.

Traditional heating system sequence of events:
1. Outside temperature drops
2. More heat is lost through the walls & windows
3. Rooms get colder - which is detected by the room thermostat
4. Thermostat 'tells' the boiler to fire/work harder (if timeclock allows)
5. Rooms get warmer again

In the above example, it isn’t until stage 4 that the boiler gets any ‘feedback’ and is able to respond to changing conditions.
The chances are that at this stage, the householder will be feeling the cold and will turn the thermostat up even further - wasting even more fuel.
If the outside temperature rises, the boiler will not respond until the rooms have become uncomfortably warm - so in addition to
adjusting thethermostat, there’ll probably be the temptation to open some windows, releasing more heat and wasting more energy

Weather Compensation Control
1. Outside temperature drops - which is detected by outdoor sensor
2. HP/Boiler will come on sending heat into house
3. Radiators get warmer to compensate for heat lost*
4. Room temperature is maintained

Therefore weather compensation is only looking to send in just the right amount of heat into the building, no more nor no less to keep it at a contant temperature. Various forms of heat pumps then will have temperature set backs built in that will allow greater use of night rate electricity.

WCC (weather compensation controls) will always be looking at the outside temperature (main factor in heating demand of a building) and calculate a desired flow temperature into the UFH/rads, this calculated flow temperature will increase in cold weather and decrease in warm.

The WCC will them compare the actual flow temperature in the rads/ufh (which reflects building temp) and compare it with the desired flow temperature (based on outdoor temp and homeowner setting) and run the heat pump if deemed necessary.

WWC is the only cost efficient way to control UFH.

One of the clearest descriptions I have ever seen

You will see other posts of mine where I thought Oil or gas plus solar thermal would be the best - but if you do the maths/return on investment etc then a HP wins every time.

JD6910

fclauson wrote: »

One of the clearest descriptions I have ever seen

You will see other posts of mine where I thought Oil or gas plus solar thermal would be the best - but if you do the maths/return on investment etc then a HP wins every time.

is this based on both systems being ON all the time and maintaining a constant temp??

PeteHeat

JD6910 wrote: »

is this based on both systems being ON all the time and maintaining a constant temp??

We are all saying the same thing just different ways of controlling the system, the Key is NO TIMERS.

I raised my concerns about the cost of LPG earlier, then I posted independent data in another thread you started

Appears you are not reading the replies?
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sheff the ref

soundskin wrote: »

The advantage of weather compensation over s-plan heating controls (timeclock & thermostat) is that is a predictive control for house temperature instead of a reactive control that will will get a standard heating controls.

Traditional heating system sequence of events:
1. Outside temperature drops
2. More heat is lost through the walls & windows
3. Rooms get colder - which is detected by the room thermostat
4. Thermostat 'tells' the boiler to fire/work harder (if timeclock allows)
5. Rooms get warmer again

In the above example, it isn’t until stage 4 that the boiler gets any ‘feedback’ and is able to respond to changing conditions.
The chances are that at this stage, the householder will be feeling the cold and will turn the thermostat up even further - wasting even more fuel.
If the outside temperature rises, the boiler will not respond until the rooms have become uncomfortably warm - so in addition to
adjusting thethermostat, there’ll probably be the temptation to open some windows, releasing more heat and wasting more energy

Weather Compensation Control
1. Outside temperature drops - which is detected by outdoor sensor
2. HP/Boiler will come on sending heat into house
3. Radiators get warmer to compensate for heat lost*
4. Room temperature is maintained

Therefore weather compensation is only looking to send in just the right amount of heat into the building, no more nor no less to keep it at a contant temperature. Various forms of heat pumps then will have temperature set backs built in that will allow greater use of night rate electricity.

WCC (weather compensation controls) will always be looking at the outside temperature (main factor in heating demand of a building) and calculate a desired flow temperature into the UFH/rads, this calculated flow temperature will increase in cold weather and decrease in warm.

The WCC will them compare the actual flow temperature in the rads/ufh (which reflects building temp) and compare it with the desired flow temperature (based on outdoor temp and homeowner setting) and run the heat pump if deemed necessary.

WWC is the only cost efficient way to control UFH.

I take it a Weather Compensation Controller will not be cheap!!

I suppose the thing people are most unsure about is that that given the super-insulation of new homes meaning a house will not lose heat as easily as older houses, therefore the walls etc. will not be as cold when the heat kicks in. Most houses with oil and rads would probably kick in early in the morning for an hour, perhaps kick in around lunch time, and kick in at intervals in the evening. Therefore subject to manual setting of the timer, a highly insulated house will not be without heat for very long. Granted in extreme temperatures, more heat will be required, but in an average Irish winter there may not be much need to deviate from the norm in terms of the timer settings.

A heatpump with underfloor and a WCC may potentially invoke a lot of cutting in and cutting out of the heatpump, which could potentially shorten the life of the heatpump. With an oil boiler and rads, the boiler kicks in and stays running for a set time. With the heatpump is there a danger of being borderline on the cut in, cut out stage the whole time. Take for example an electric oil filled radiator, that could potentially cut in 5 or 6 times an hour. Will that happen with a heatpump and WCC depending on the location of the Weather sensor and the number of times that the Sun could appear and disappear in say an hour???

Condenser

sheff the ref wrote: »

I take it a Weather Compensation Controller will not be cheap!!

I suppose the thing people are most unsure about is that that given the super-insulation of new homes meaning a house will not lose heat as easily as older houses, therefore the walls etc. will not be as cold when the heat kicks in. Most houses with oil and rads would probably kick in early in the morning for an hour, perhaps kick in around lunch time, and kick in at intervals in the evening. Therefore subject to manual setting of the timer, a highly insulated house will not be without heat for very long. Granted in extreme temperatures, more heat will be required, but in an average Irish winter there may not be much need to deviate from the norm in terms of the timer settings.

A heatpump with underfloor and a WCC may potentially invoke a lot of cutting in and cutting out of the heatpump, which could potentially shorten the life of the heatpump. With an oil boiler and rads, the boiler kicks in and stays running for a set time. With the heatpump is there a danger of being borderline on the cut in, cut out stage the whole time. Take for example an electric oil filled radiator, that could potentially cut in 5 or 6 times an hour. Will that happen with a heatpump and WCC depending on the location of the Weather sensor and the number of times that the Sun could appear and disappear in say an hour???

Its usually standard on heat pumps so no additional cost. A heat pump on weather comp would not usually cut in more than 3-4 times a day in winter. The sensor should be on a north facing wall and so is not affected by the sun. The outdoor temp is also taken over a period of time and arrives at an average temp so it does not react to periodic changes in temp.
No matter how you run an oil boiler it will not beat a well designed and installed heat pump for running costs in a year unless you run your oil boiler like an absolute miser and even then it probably won't come close.

JD6910

does anyone know what happens in reality to the heat pump system after 15 years???
is there heat pumps in ireland for over 15 years? does the unit need to be replaced completely or does the compressor need to be changed - any idea of costs? Surely this needs to be factored in to decision making at the outset.

Having to "upgrade" or re-vamp the heat pump every 15 or even 20 years for say a cost of €3K is a big negative on top of the capitial costs!!!! over the life span of the house and owner a person (say 60 years) may have to "upgrade" the heatpump 3 times!!!!!

Condenser

JD6910 wrote: »

does anyone know what happens in reality to the heat pump system after 15 years???
is there heat pumps in ireland for over 15 years? does the unit need to be replaced completely or does the compressor need to be changed - any idea of costs? Surely this needs to be factored in to decision making at the outset.

Having to "upgrade" or re-vamp the heat pump every 15 or even 20 years for say a cost of €3K is a big negative on top of the capitial costs!!!! over the life span of the house and owner a person (say 60 years) may have to "upgrade" the heatpump 3 times!!!!!

The heat pump fairies come and take the compressor from under your pillow and you get a 2k rebate.

I think you should take airs advice above or else just go and whack in an oil boiler as you clearly have no intention of reading the posts above or else your just on the wind. Either way I think advice is wasted on you.

sheff the ref

Sounds like a very effective system.

Basically in short, its cheaper to maintain temperature than to heat from cold.

Condenser wrote: »

Its usually standard on heat pumps so no additional cost. A heat pump on weather comp would not usually cut in more than 3-4 times a day in winter. The sensor should be on a north facing wall and so is not affected by the sun. The outdoor temp is also taken over a period of time and arrives at an average temp so it does not react to periodic changes in temp.
No matter how you run an oil boiler it will not beat a well designed and installed heat pump for running costs in a year unless you run your oil boiler like an absolute miser and even then it probably won't come close.

sheff the ref

JD6910 wrote: »

does anyone know what happens in reality to the heat pump system after 15 years???
is there heat pumps in ireland for over 15 years? does the unit need to be replaced completely or does the compressor need to be changed - any idea of costs? Surely this needs to be factored in to decision making at the outset.

Having to "upgrade" or re-vamp the heat pump every 15 or even 20 years for say a cost of €3K is a big negative on top of the capitial costs!!!! over the life span of the house and owner a person (say 60 years) may have to "upgrade" the heatpump 3 times!!!!!

What is the life of an Oil Boiler??? I am sure there are also maintenance costs over the long term.

Condenser

sheff the ref wrote: »

Sounds like a very effective system.

Basically in short, its cheaper to maintain temperature than to heat from cold.

Yes, especially in the highly insulated houses being built at the moment. It takes very energy to maintain the house and therefore ufh systems only need to be running for relatively short periods of time in order to bring the house to temp.

Allow the house to cool slightly at night so its comfortable to sleep and recharge an hour or so before you wake in the morning.

JD6910

Condenser wrote: »

The heat pump fairies come and take the compressor from under your pillow and you get a 2k rebate.

I think you should take airs advice above or else just go and whack in an oil boiler as you clearly have no intention of reading the posts above or else your just on the wind. Either way I think advice is wasted on you.

It was a good debate until condenser threw the toys out of the cot!!!!!!!:p

So what is the reality after 15 years of having the heat pump????

Ya ya your advice to" whack" in the heat pump in a low energy near passive house is great "advice"!!!!!!:D you need to read and listen to the detail - a heat pump is perfect in a house that was banged up in the Celtic tiger and has a constant demand for heat. The super insulated low energy homes of the last few years don't need heat pumps. Im simply suggesting traditional heating systems may have a place is these low energy homes.

PeteHeat

JD6910 wrote: »

Ya ya your advice to" whack" in the heat pump in a low energy near passive house is great "advice"!!!!!!:D you need to read and listen to the detail - a heat pump is perfect in a house that was banged up in the Celtic tiger and has a constant demand for heat. The super insulated low energy homes of the last few years don't need heat pumps. Im simply suggesting traditional heating systems may have a place is these low energy homes.

Actually the advice is the exact opposite for heat pumps or for a combination of heat sources using a buffer.

It has been explained in detail why you don't need a high temperature system in a low energy home however they haven't been ruled out just don't use 1990's heating controls in a 2012 house..
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