To zone UFH or not to zone?

just do it

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 factor left out here is wind. Probably not as much an issue in a new build with good airtightness, but in builds with poor airtightness wind makes a huge difference, possibly more so than temperature. This was borne out by a recent article in the lastest CI magazine (can't think of the new name- passive plus?)

just do it

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!!!!!

sheff the ref wrote: »

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

Oil boiler needed to be changed last year in a 2004 build. I think it was €1,500 but would need to check that. So it seems the if the new one only lasts for the same amount of time it will be €3,000 every 15 years;)

PeteHeat

The unofficial average life expectancy of a new gas boiler is 10 years.

All boilers will require replacement in the future be they oil, gas, pellet, wood or heat pumps.

Cars and vans depreciate at a faster rate and they all have a limited life expectancy.

Like ourselves even mechanical objects don't last forever.

.

just do it

just do it wrote: »

Oil boiler needed to be changed last year in a 2004 build. I think it was €1,500 but would need to check that. So it seems the if the new one only lasts for the same amount of time it will be €3,000 every 15 years;)

Out of interest this change was part of an overall energy upgrade to a 150m2 dormer. The primary energy demand was 240kWh/m2/yr prior to the upgrade and reduced to 175kWh/m2/yr after.

175kWh/m2/yr!

That puts where we are with new builds in perspective!

fclauson

just do it wrote: »

175kWh/m2/yr!

and my new build is 13.5Kw/M2/yr

just do it

FC
When are you moving in?;)

sheff the ref

Basically its a case of Maths.

Cost of Oil, Rads, Boiler (and replacements if necessary), Controller, Tank and any other costs versus the Cost of the Heatpump, Excavation/Boring, Controller and Underfloor Heating.

just do it wrote: »

Oil boiler needed to be changed last year in a 2004 build. I think it was €1,500 but would need to check that. So it seems the if the new one only lasts for the same amount of time it will be €3,000 every 15 years;)

just do it

sheff the ref wrote: »

Basically its a case of Maths.

and compliance with part L!

Cost of Oil, Rads, Boiler (and replacements if necessary), Controller, Tank and any other costs versus the Cost of the Heatpump, Excavation/Boring, Controller and Underfloor Heating.

one worry I have with ground source is maintenance of the underground network of pipes. An oil boiler or an air source hp is much easier to get at.

sheff the ref

In theory the pipes would never have to be maintained as each pipe off the manifold is not supposed to be joined and therefore one closed loop leaves and returns to the connections on the manifold. The only issues I came across would have arisen where the pipes were damaged when the excavated collector area was being filled in. A borehole collector also consists of a closed loop and that can be pulled up out of the ground quite easily. For a small house only one borehole is required.

As regards inside the house, from a practical point of view radiators are handy for hanging clothes so 100% underfloor is not ideal either.

just do it wrote: »

and compliance with part L!

one worry I have with ground source is maintenance of the underground network of pipes. An oil boiler or an air source hp is much easier to get at.

dathi

As regards inside the house, from a practical point of view radiators are handy for hanging clothes so 100% underfloor is not ideal either.[/QUOTE]

unjointed thinking again drying clothes on your rads will increase the humidity levels in your house, and increase the amount of ventilation needed to prevent mould growth ,which in turn will increase your heatload.

sheff the ref

I dont think anyone dries all their clothes indoors, however in emergency situations its always handy to have that option.

That said I know some people that have an internal clothes line/frame in their utility room. Seemed like a handy thing to have but if it contributes to mould growth, then it may not be worth the hassle.

dathi wrote: »

As regards inside the house, from a practical point of view radiators are handy for hanging clothes so 100% underfloor is not ideal either.

unjointed thinking again drying clothes on your rads will increase the humidity levels in your house, and increase the amount of ventilation needed to prevent mould growth ,which in turn will increase your heatload.[/QUOTE]

fclauson

sheff the ref wrote: »

I dont think anyone dries all their clothes indoors,

WHy not if you have an HRV then the moist extracted air will carry more warmth (higher enthropy) than dry air hence you get better heat extraction

PeteHeat

If someone builds a house they can go as far putting a large sliding door in the back or side and drive the car in to dry it off, it's their home so their choice.

Being practical, radiators are designed to emit heat at a certain rate, they are sized with reasonable accuracy to suit the room they are installed in, hanging clothes on the radiators prevents the heat being dissipated as intended resulting in cold spots or even cold rooms.

Being practical If a customer wishes to dry clothing in the house I would suggest designing in a decent sized utility room which would double as a plant room, fit the boiler, buffer and hot water cylinder in the utility room allowing any heat loss from the heating appliance and hot water storage to dry the clothes that can be arranged to hang at a high level.

Too much moisture in a HRV is IMO asking for problems with the filters and the ducting, they have had these problems in the USA with mold growth in the ducting leading to health issues for the occupants.
.

fclauson

sheff the ref wrote: »

,, A borehole collector also consists of a closed loop and that can be pulled up out of the ground quite easily. For a small house only one borehole is required.

If you can pull your borehole pipe work up then its not installed correctly.

Most place outside ireland now insist you fill the borehole with a clay compound so as to get a good thermal connection between pipe work and the ground.

If you do not do this then you are relying on air to pipe work conduction which will be very poor.

If you are assuming the hole will be filled with water then you have to consider when the water level drops and the upper section of the pipe work is now again hanging in free air

sheff the ref

If you go 100m below the ground it is rare that you dont hit water

fclauson wrote: »

If you can pull your borehole pipe work up then its not installed correctly.

Most place outside ireland now insist you fill the borehole with a clay compound so as to get a good thermal connection between pipe work and the ground.

If you do not do this then you are relying on air to pipe work conduction which will be very poor.

If you are assuming the hole will be filled with water then you have to consider when the water level drops and the upper section of the pipe work is now again hanging in free air

fclauson

true - but the correct way is to plug the hole to have all the pipework incontact all the time - anything else will reduce efficiency