Nibe 1245 - enough hot water for a family?

uptowngirly

I'm still researching heating options and am now 100% decided on a GSHP. There are a couple of makes/models that I've had quotes on and seem to have good data to back them up.

However - I was also thinking of installing solar panels for DHW. I've been getting conflicting reports (surprise surprise) on the need for solar panels when a GSHP is installed. I don't like the idea of needing a massive buffer tank that takes up lots of room in the house but with the above heat pump, it also gives 180 litres of hot water (and it's the size of a fridge freezer for the entire unit).

My question is (finally:o)
Has anyone used the Nibe 1245 and did it supply enough hot water for your family (we have two kids as well as myself and my partner)? I'm worried that a 180 litre tank would not be enough water for the kids bath and then a nice bath for me in the evening too! We also plan to have a power shower in the master ensuite, and I've heard they're a demon for draining water tanks!

Mods- if I'm not allowed mention the name of the unit, I'm really sorry and please delete (I did read the charter and I know I can't name the company but think the heat pump brand is ok)

Splinter Cell

Hi uptowngirly,
I am researching GSHP also and have put the F1245 at the top of my list. I don't see the need for solar panels, the sun is heating the ground also, why would you need to spend €€€ on both to do the same thing? I also don't see the need for a huge buffer tank but am fitting eco-shower heads, use < 6lpm. We have 2 kids also, 180l will be more than enough for 4 showers later on with enough left over for normal hot tap usage. I doubt it will do for 2 baths though and any vendors that I spoke to have said that power showers are a no-no.
Out of curiosity, what kW are you looking at and how was it calculated?
SC.

uptowngirly

Hey Splintercell

We recently changed our house design totally from a bungalow to a dormer so I have to get quotes again from the three GSHP's I was looking into. The first house was 260sqm and we were quoted for an 8kw heat pump, a 12kw and also a 14kw:eek: which to be honest was excessive if even minimum regulations were followed for insulation levels.

We will be aiming for uvalues of .15 for the floor, .18 for walls, .16 for roof and .9 for windows. We will also be applying an airtightness membrane and taping and doing wind blower test before and after slabbing. We will also be installing a MHRV.

Our dormer is now looking at being 280sqm so I presume we will be looking at the 12kw option (but will wait until I see what's specced!)

If we go for the Nibe heat pump, I think we'll use the 1145 and put a 300 litre cylinder with that as even a 10 minute eco shower will use 50 litres of water and I'd spend double that in the shower every day easily. We also will have three showers and I would like the option of having one of these as a power shower so the more I look at the 180l hot water cylinder, the more I can't see it being enough for us, but I'm open to correction!!

We are decided on henco underfloor heating (it seems to be one of the better ones on the market) with 75mm screed on the ground floor and 35mm easy screed on the first floor.

HTH

Splinter Cell

Our's is a story and 1/2, 210 sq m, average u values < .12 with mhrv. My DEAP results show 3.8kW heat use in the coldest month (Jan), plus DHW requirements. Just for grins, I plugged your average u values (~.17) into our spec and got 4.5kW. Now, that is nowhere near scientific based on different size, orientation, ammount of glazing etc. so please don't accept this as meaningful. But unless your house is at the bottom of a dark, damp hole, I doubt that you will require a 14kW gshp! My advice, hire an energy consultant and have them do the calculations for you. For < €200, you will be better informed and you will need it for your BER anyway.

L driver

Uptowngirly,
Do you work naked in a coalpit.... 20+ min a day in a shower!:eek:

freddyuk

uptowngirly wrote: »

I'm still researching heating options and am now 100% decided on a GSHP. There are a couple of makes/models that I've had quotes on and seem to have good data to back them up.

However - I was also thinking of installing solar panels for DHW. I've been getting conflicting reports (surprise surprise) on the need for solar panels when a GSHP is installed. I don't like the idea of needing a massive buffer tank that takes up lots of room in the house but with the above heat pump, it also gives 180 litres of hot water (and it's the size of a fridge freezer for the entire unit).

My question is (finally:o)
Has anyone used the Nibe 1245 and did it supply enough hot water for your family (we have two kids as well as myself and my partner)? I'm worried that a 180 litre tank would not be enough water for the kids bath and then a nice bath for me in the evening too! We also plan to have a power shower in the master ensuite, and I've heard they're a demon for draining water tanks!

Mods- if I'm not allowed mention the name of the unit, I'm really sorry and please delete (I did read the charter and I know I can't name the company but think the heat pump brand is ok)

Can you confirm the temperature of the hot water you have been told will be available from the GSHP? Will the GSHP provide all the DHW requirement at the correct temperature or will it need back up from another heat source.?

uptowngirly

Now L-Driver - that is just bold!! Bet there's lots of people who could spend that amount of time in a shower

FreddyUK - the temp for the DHW is 60c. It will not have a back up heat source.

L driver

uptowngirly wrote: »

Now L-Driver - that is just bold!! Bet there's lots of people who could spend that amount of time in a shower

Not on my own;)
Could you let us know more about the system, COP in winter with -10c outside, has the supplier given any figures in writing etc.

Condenser

uptowngirly wrote: »

Now L-Driver - that is just bold!! Bet there's lots of people who could spend that amount of time in a shower

FreddyUK - the temp for the DHW is 60c. It will not have a back up heat source.

It will have a back up heat source. It will require the immersion to bring it to that temperature. If you run a heat pump to that temp the compressor won't last 5-6yrs.

I think the supplier has been telling pork pies.

Also you should reconsider using two different screed depths, they will have two different reaction times which is not good for a HP, as it will cause it to cycle more frequently/

Splinter Cell

uptowngirly wrote: »

Now L-Driver - that is just bold!! Bet there's lots of people who could spend that amount of time in a shower

FreddyUK - the temp for the DHW is 60c. It will not have a back up heat source.

Why is your DHW at 60c? Your skin won't tolerate > 40c. Your UFH should not require > 30-35c to maintain a comfortable room temeprature if it has been designed properly. I would imagine that the immmersion is only to bring the tank to > 60c for legionella, maybe once a week?

uptowngirly

I think that there must obviously be an immersion to bring it up to 60c - that is on the luxury setting (you need to press a button for it to do this) It would mean more hot water in my head because you could mix the bath with cold as well and actually have a chance of filling it, but I can see where I'm going wrong.

To be fair to the manufacturer, they didn't tell me that there was no additional heat source - when I read the question I thought the OP was asking me if I was going to install a wood pellet stove or a back burner or something along those lines - my mistake

My main issue is the size of the DHW tank. The two other brands that I have looked seriously at are (and if I'm breaking the code, please delete mods - but I'm not mentioning suppliers) are the watterkotte heat pump and the heliotherm heat pump. The only problem was that both had 500/1000 litre buffer tanks and were speccing for 12KW and 14KW size pumps which seemed like overkill on a 260sqm well insulated house.

These buffer tanks take up serious amount of room!

Thanks everyone for their input and advise - it's much appreciated

Condenser

Splinter Cell wrote: »

Why is your DHW at 60c? Your skin won't tolerate > 40c. Your UFH should not require > 30-35c to maintain a comfortable room temeprature if it has been designed properly. I would imagine that the immmersion is only to bring the tank to > 60c for legionella, maybe once a week?

When the tank is only 180L it will need to be heated to about 65C constantly, otherwise you won't have enough water to last 2 showers. An average shower takes 9-11 litres a minute. Some power showers can take up to 20L/min. If the water was maintained in the tank at 50C you would get about 120L of useable hot water, which for Uptowngirly would be half a shower

Splinter Cell

Condenser wrote: »

If the water was maintained in the tank at 50C you would get about 120L of useable hot water

Forgive my lack of understanding here but why is this? My assumption would have been that a 180l tank @ 50C would give > 180l of usable hot water @ 40d, filling a bath for instance, when mixed with cold water.

Condenser

Splinter Cell wrote: »

Forgive my lack of understanding here but why is this? My assumption would have been that a 180l tank @ 50C would give > 180l of usable hot water @ 40d, filling a bath for instance, when mixed with cold water.

Its because cold water will be entering the tank to replace the hot water you are extracting so you'll never get the volume of water from the tank that the size would suggest. The only way to overcome this is to increase the temp of the water so more cold is mixed with it when running showers and baths, therefore giving more volume. Because of this its not a good idea to run a HP with a small dhw cylinder as you'll be relying more on the immersion than the HP for hot water

Splinter Cell

@ Condenser,

Yeah, that makes sense, the cold water refilling the tank as it drains is cooling the hot water still left in it, making it less effective. I was thinking in terms of the hot water draining from the tank until a low level sensor caused it to refill.

Now that is making me rethink ... leaving legionella control aside for a second, which is better, a "storage" tank that you draw water from for use or a "heat exchanger" tank where fresh water is used, drawing heat from the water in the tank through a coil?

Also, what is the ideal way to run the UFH? Connected directly to the GSHP (assuming UFH pipes are appropriate pitch, length and no stats) or connected to the tank, using it as a buffer?

Thanks for sharing your knowledge with us

Condenser

Splinter Cell wrote: »

@ Condenser,

Yeah, that makes sense, the cold water refilling the tank as it drains is cooling the hot water still left in it, making it less effective. I was thinking in terms of the hot water draining from the tank until a low level sensor caused it to refill.

Now that is making me rethink ... leaving legionella control aside for a second, which is better, a "storage" tank that you draw water from for use or a "heat exchanger" tank where fresh water is used, drawing heat from the water in the tank through a coil?

Also, what is the ideal way to run the UFH? Connected directly to the GSHP (assuming UFH pipes are appropriate pitch, length and no stats) or connected to the tank, using it as a buffer?

Thanks for sharing your knowledge with us

A fresh water system is always the best system to use with a HP. You won't need any immersions to back it up as the water won't leave the tank, its merely there to heat the fresh cold water. You will need a larger tank but you'll heat your hot water for at least 1/4 of the cost. In a small tank the last 15C is the most important as this is the band where heating is called for so you'll be heating predominatly with the immersion.

Regarding the ufh, the most efficient way is to run the system straight to the ufh, with no stats, using the screed as the buffer. A good heat pump should have a decent weather compensation system which will optimise the system at all times. This will increase the efficiency of the unit and lower your running costs.

The ufh design is very important. Most ufh systems in ireland are designed to oil boiler spec, a ufh designed for a heat pump will have a greater density of pipe and shorter loops to allow the system work on the lowest temp possible.

freddyuk

Precisely why I asked the question!
GSHP is a great system to get to a certain temperature but it requires a boost for DHW and that can make the difference if the system is not properly planned. As explained above the amount of stored water is important as it dictates the amount of usable water in any one session, for the average family.
Any company that does not explain fully what makes their system tick should be avoided.

The number of people that have contracted legionella from a domestic hot water system is....????

Condenser

freddyuk wrote: »

Precisely why I asked the question!
GSHP is a great system to get to a certain temperature but it requires a boost for DHW and that can make the difference if the system is not properly planned. As explained above the amount of stored water is important as it dictates the amount of usable water in any one session, for the average family.
Any company that does not explain fully what makes their system tick should be avoided.

The number of people that have contracted legionella from a domestic hot water system is....????

It doesn't require a boost if the system has a fresh domestic hot water system but most do not. Its a cost thing. Keeping the cost down against suppliers who use a FDHW system makes your product more appetising and just avoid telling the customer the full facts behind the system

pom2pom

Hi,

Just to put fuel on the fire, nibe 1230 ( only test I could find and that is with only a 160l tank ) acctually gives you 238l of 40 degree water.

So uptowngirly could atleast get enough water for one shower for herself.

Condenser

pom2pom wrote: »

Hi,

Just to put fuel on the fire, nibe 1230 ( only test I could find and that is with only a 160l tank ) acctually gives you 238l of 40 degree water.

So uptowngirly could atleast get enough water for one shower for herself.

If heated to ?C with the immersion. I would say at least 65 or 70C

pom2pom

Max water temp is 55 degrees!

Also there are other that gives you more water and warmer water. Diplomat Optimum G2 for instance. But as uptowngirly said a 1145 with a standalone 300l is very good if you use lots of warm water!

Condenser

pom2pom wrote: »

Max water temp is 55 degrees!

Also there are other that gives you more water and warmer water. Diplomat Optimum G2 for instance. But as uptowngirly said a 1145 with a standalone 300l is very good if you use lots of warm water!

Max is 55C from the heat pump. The immersion can bring it as far as 80C. You couldn't leave that water at 55C constantly as it will breed legionella.

There is no way you will get 238L of 40C from a 160L tank if the water is 55C, its not physically possible. Think about it.

pom2pom

I guess the test lies , http://www.radron.se/Documents/Tester%20med%20annat%20betygssystem/tabeller/060217_02_varmepumpar.pdf, since its an english bord but the test says that they tested how much 40 degree water they could get if they continously used the water without the immersion helping.

Also, for legionella most pumps heats up the water once every 14-90 days.

freddyuk

Here is some information:
The Facts

Legionnaires' disease is an opportunistic infection caused primarily by the inhalation of Legionella bacteria in the form of a mist (aerosol), as produced by contaminated showers, cooling towers, whirlpool spas, and other water systems. Because Legionella bacteria lives in most natural water sources and in mains water and bore hole supplies, they readily enter, and subsequently colonise, the water systems of buildings. They can multiply rapidly in water at temperatures between 20°C - 45°C.As the temperature rises above 60°C the majority of legionella will be killed within 5 minutes. Below 20°C it remains dormant. Maintaining water temperature above 50°C and below 20°C is therefore the main method of controlling legionella in domestic water systems as recommended by the Department of Health, and the UK Health and Safety Commission.

CAUTION: Hot water temperatures that do not cause scalding are ideal for the legionella bacteria to grow in water system....but hot water temperatures that kill legionella bacteria will cause scalding.


My question is what happens in the "cool" water at the bottom of the storage cylinder. Unless the whole cylinder is heated to 60° there is a potential breeding ground at the lower part of the cylinder. The sensor on most cylinders is 1/3 rd of the way up and the temperature at the bottom is quite cool. If you turn down your temperature to 50 - 55° (which is where most people will have it set) then surely the problem, if it exists, is compounded. The problem would only occur if the shower being used emptied all the "hot" water and sprayed the cooler water. So instead of using TMV to keep the scalding water cooler we should be fitting a stop control when the temperature is too low?
I assume the heating element in the Heat pump system is about halfway up the cylinder?

L driver

Hello,
So uptowngirly and splinter cell any updates on the gshp? Is the dhw tank built into the nibe? What did you go for?

Troy McClure

There seems to be alot of info going over and back here not to mention disagreement.
If I wanted to talk to someone who is well versed in all these matters who would I call.?

Someone mentioned an energy consultant for less than €200. Where do I find such as person thats not one of these many over night start ups..

Also the is alot of abreviated language used throughout the thread would someone like to give a glossary on this ?

uptowngirly

Well LDriver!

I've decided that I cannot live without the ability to have nice long showers!!! So, we're going to go with the Nibe 1145 with a separate 300 litre cylinder. We were quoted for the VBAS tank (1000 litre tank with buffer included) that you use if you're going with solar panels, but the cost was prohibitive.

Mind you, we've plenty of time yet, so we'll wait and see!

@TroyMcClure:

GSHP - Ground Source Heat Pump
DHW - Domestic Hot Water
TMV - Thermostatic Mixing Valve
UFH - Under Floor Heating

L driver

Hello,
Think I will have along one too when we move in! Is your 300l a thermal store with a coil/plate heat exchanger for DHW? What kW is the nibe hp and what made up your mind to choose it?

Troy McClure

Condenser wrote: »

The ufh design is very important. Most ufh systems in ireland are designed to oil boiler spec, a ufh designed for a heat pump will have a greater density of pipe and shorter loops to allow the system work on the lowest temp possible.

condenser
We are looking at Ufh but want to use it on oil. However in a few years we want to put in a heat pump when we can afford to. What should we do to future proof this senario witdesign etc, and to allow a heat pump to be connected in the future. We want to use solar so should we use a buffer tank to use it for heating. Who would I talk to about all this hot water usage calcs and tank sizes?

Condenser

Troy McClure wrote: »

condenser
We are looking at Ufh but want to use it on oil. However in a few years we want to put in a heat pump when we can afford to. What should we do to future proof this senario witdesign etc, and to allow a heat pump to be connected in the future. We want to use solar so should we use a buffer tank to use it for heating. Who would I talk to about all this hot water usage calcs and tank sizes?

Depending on pipe sizes used your ufh should have spacings of between 100-120mm and loop lengths of between 80-100m. The greater the density of pipe the lower the water temp you will require to heat the house to a given temp.
Regarding sizing of the Buffer. You should allow about 15L per kw output of the heat pump. Unless you are just putting in solar to meet planning requirements I wouldn't bother with solar. It makes no financial sense if going with a HP. If you don't go with solar you can drop the buffer too. Weather compensation is a better system than using stats and maximises the heat pump efficiency

Also get the dimensions of your flow/return pipework right. What works for an oil boiler won't work for a HP. And put any additional piping you may need in position now, so its a staight swap when the time to fit the HP comes

Troy McClure

As mentioned we are starting with oil but want to have gshp eventually. With that in mind why do you think solar is a waste of time? Can Weather compensation be used with oil.? Is it generally a good idea? is it expensive?

Condenser

Troy McClure wrote: »

As mentioned we are starting with oil but want to have gshp eventually. With that in mind why do you think solar is a waste of time? Can Weather compensation be used with oil.? Is it generally a good idea? is it expensive?

Unless you don't plan on installing the GSHP for years then I don't see the point in getting solar. You'll never see a return on them. I'd either keep the money in your pocket until you buy a HP and buy a good one, or else upgrade your insulation. Solar doesn't stack up in new builds as far as I'm concerned.
You can get weather compensation systems for oil boilers but they don't work as well as they do with HPs as higher water temps don't decrease a boilers efficiency as they do a HPs.
You could install cheap stats in the meantime and then remove them when you upgrade to the HP

Troy McClure

Condenser
Would it be easy to change from stats to weather comp down the road without major work?
People on the Solar poll thread seem happy with it, however they dont say if it's retro fit or new build. I would have though heating water without cost would have to have payback. Could the UFH not run to degree from solar then boiler to make savings?

Condenser

Troy McClure wrote: »

Condenser
Would it be easy to change from stats to weather comp down the road without major work?
People on the Solar poll thread seem happy with it, however they dont say if it's retro fit or new build. I would have though heating water without cost would have to have payback. Could the UFH not run to degree from solar then boiler to make savings?

It wouldn't be a problem. Just run a cable from a north facing wall (so you can fit the stat, back to the point where you intend fitting the HP in future. Its very simple after that.
You'd need a huge amount of solar panels in order to make any contribution to your UFH. As i said, if you're going to change to a HP at some stage I wouldn't bother with them. Personally I'd keep my money in my pocket and buy a really good heat pump when the time comes, the savings you'll make in the meantime wouldn't be worth considering.

Troy McClure

Would you need to run that cable at the build stage or would it be possible down the road in an airtight house?

If you dont use solar how would you fulfill building regs? HRVS wont do it..

Condenser

Troy McClure wrote: »

Would you need to run that cable at the build stage or would it be possible down the road in an airtight house?

If you dont use solar how would you fulfill building regs? HRVS wont do it..

Its best to run at building stage, as would be any piping you would require for the heat pump. Remember that the piping that would be ran to your manifolds on a Oil burner install may not be large enough to give you the flow rates you need with a HP.

Regarding the building regs, that would be the only argument I could see to merit installing the solar now. I don't know if a pellet stove or log stove would qualify as a renewable for you, I think you mentioned installing one in your house elsewhere?

Troy McClure

Yeah we want to use a stove to keep airtightness.

Troy McClure

You have me thinking now.. What kind of cost is an installed system like the Nibe 1245 spoken about in this thread?

liamolaighin

300 litre tank, underfloor, controls & Nibe 1145 heatpump €19000. Also ground loop included but excavation not. Then you also have the plumbing for the rest of the house!! 3100 sq foot house

Greenlight

A nibe fighter 1245 12kw should cost in the region of 12k.
Having an 1145 and VPB will however reduce your hot water run time and give you a large store. This should be only necessary for very very large hot water consumption.

A 1245 will have more than enough hot water for the average family. Even with power showers. Hot water compressor time usually average 15-20% of your total compressor time. It will do an extra hot water (luxury) cycle via the immersion every 14 days to kill off legionella.