New build with air to water heating system

blindside88

Hi Guys,

Myself and my wife are planning on moving in the new year and are about to put a deposit down on a new build which will start construction in January. The size is perfect for what we want. My only concern is the heating system. It’s air to water underfloor heating and I have no experience of this. The new house is A rated and has pumped cavity as well as insulated slab. Our current house is gas central heating with a stand alone stove (C rated) so we’re just a bit anxious as it’s a bit of an unknown for us. The only negatives I can think of are:
1) getting used to not being able to change the temperature of the house suddenly
2) loosing a lot of the hot press for what I imagine will be a very big tank.

Any input or advise would be much appreciated. I attached the plan of the house.

Thanks

MicktheMan

blindside88 wrote: »

Hi Guys,

Myself and my wife are planning on moving in the new year and are about to put a deposit down on a new build which will start construction in January. The size is perfect for what we want. My only concern is the heating system. It’s air to water underfloor heating and I have no experience of this. The new house is A rated and has pumped cavity as well as insulated slab. Our current house is gas central heating with a stand alone stove (C rated) so we’re just a bit anxious as it’s a bit of an unknown for us. The only negatives I can think of are:
1) getting used to not being able to change the temperature of the house suddenly
2) loosing a lot of the hot press for what I imagine will be a very big tank.

Any input or advise would be much appreciated. I attached the plan of the house.

Thanks

1) Nothing wrong with air to water heat pump/uf system if (and its a big if) the house is built properly. Underfloor (uf) heating systems are low temperature systems with very long response times which are designed to maintain a comfortable indoor temp over a continuous timeframe because of the low heat loss of modern builds, whereas high temperature systems such as your gas/rads system are rapid response systems designed to make up for the much higher heatloss of older builds.
You will control your uf heating completely differently than a rad system i.e. generally when it is set up you leave it alone rather than turning it on/off & boosting a rads system.
2) What big tank?
FYI, the bolded bit above is generally considered a poor specification nowadays.

blindside88

MicktheMan wrote: »

1) Nothing wrong with air to water heat pump/uf system if (and its a big if) the house is built properly. Underfloor (uf) heating systems are low temperature systems with very long response times which are designed to maintain a comfortable indoor temp over a continuous timeframe because of the low heat loss of modern builds, whereas high temperature systems such as your gas/rads system are rapid response systems designed to make up for the much higher heatloss of older builds.
You will control your uf heating completely differently than a rad system i.e. generally when it is set up you leave it alone rather than turning it on/off & boosting a rads system.
2) What big tank?
FYI, the bolded bit above is generally considered a poor specification nowadays.

Thanks very much for that. I’m not from a building background but I had assumed that there would be a large hot water tank in the hot press as there is no immersion and the hot water is provided by the heating system. I could be wrong in that.
On the insulation I had thought I had seen it in the detailed spec (attached now) but can’t see where I got that from now.

Gumbo

blindside88 wrote: »

Hi Guys,

Myself and my wife are planning on moving in the new year and are about to put a deposit down on a new build which will start construction in January. The size is perfect for what we want. My only concern is the heating system. It’s air to water underfloor heating and I have no experience of this. The new house is A rated and has pumped cavity as well as insulated slab. Our current house is gas central heating with a stand alone stove (C rated) so we’re just a bit anxious as it’s a bit of an unknown for us. The only negatives I can think of are:
1) getting used to not being able to change the temperature of the house suddenly
2) loosing a lot of the hot press for what I imagine will be a very big tank.

Any input or advise would be much appreciated. I attached the plan of the house.

Thanks

Nothing wrong with A2W and UFH, and in fact, if I was building a new house I'd build to this spec along with external Insulation and Solar PV if funds allowed.

UFH is designed to be left on 24/7. You control the room temp using the stats. You cannot come home in the evening and switch it on thinking it will heat the house up like a traditional rad as it has to heat through the floor slab first.

The A2W aids this as its using renewable energy to keep the water hot.

blindside88 wrote: »

The new house is A rated and has pumped cavity as well as insulated slab.

Just as you say, you have no building experience, don't let these items blur your vision as they are standard and mandatory. You'll find the house in ballymun, Dublin being built currently will also have insulated slab and be A rated.

blindside88 wrote: »

Our current house is gas central heating with a stand alone stove (C rated) so we’re just a bit anxious as it’s a bit of an unknown for us. The only negatives I can think of are:
1) getting used to not being able to change the temperature of the house suddenly
2) loosing a lot of the hot press for what I imagine will be a very big tank.

Current house built in the early 00's ? C Rated is quite good.

1) You can change the temp of the house. he rooms will contain stats.
2) Normal for every new house being built at present, smallest tank/cylinder going in nowadays is 300L

Latro

If this house is build to A rating spec the heating shouldn't cost you more than 40 euro on average a month with heat pump on and internal temperature at 21 degrees all the time. Once set properly you switch it on and forget about it.

Also thermostats are not great controls for underfloor heating. You'd be better off using weather compensating curve method, the option that is available in any modern heat pump.

blindside88

Thanks for all of the input so far. Are there any disadvantages or drawbacks to A2W that I’m missing or anything about the spec of that house that would be of concern?

Eric Cartman

blindside88 wrote: »

Thanks for all of the input so far. Are there any disadvantages or drawbacks to A2W that I’m missing or anything about the spec of that house that would be of concern?

those systems are not as effective as ground to water heat pumps , the air ones are designed for climates a bit warmer than ours, in summer you'll get say 4kw for every 1kw of electricity but in winter it can drop as low as 1.8kw of heat for every 1kw of electricity so I would still expect the bills to increase in winter quite a bit.

Also treat it like a gas boiler, get it serviced every year, get the heating system flushed every 5 years or so.

blindside88

Eric Cartman wrote: »

those systems are not as effective as ground to water heat pumps , the air ones are designed for climates a bit warmer than ours, in summer you'll get say 4kw for every 1kw of electricity but in winter it can drop as low as 1.8kw of heat for every 1kw of electricity so I would still expect the bills to increase in winter quite a bit.

Also treat it like a gas boiler, get it serviced every year, get the heating system flushed every 5 years or so.

Thanks for that. Should it still be more cost effective that gas/oil to run or is the real benefit to the environment rather than my pocket?

Latro

Eric Cartman wrote: »

those systems are not as effective as ground to water heat pumps , the air ones are designed for climates a bit warmer than ours, in summer you'll get say 4kw for every 1kw of electricity but in winter it can drop as low as 1.8kw of heat for every 1kw of electricity so I would still expect the bills to increase in winter quite a bit.

Also treat it like a gas boiler, get it serviced every year, get the heating system flushed every 5 years or so.

What is "quite a bit"? 100sqm property at 50kWh/sqm/year at average COP of 3 that's about 40euro/month from October till end of March.


Ground source in comparison to air source is wasted money.
You invest around 7k more into HP+collector to save maybe 100 euro per year on electricity on system that has 15-20 years life span and that without even taking into consideration replacing expensive brine in ground collector every few years. Fingers crossed the ground collector doesn't leak before that time or you are up for huge expense.
Ireland is perfect for A2W, maybe a bit too high in humidity at low temps but still.

Eric Cartman

blindside88 wrote: »

Thanks for that. Should it still be more cost effective that gas/oil to run or is the real benefit to the environment rather than my pocket?

I suppose the saving over oil is no tank , over gas its the standing charge and another bill in the door, over both I suppose as electricity generation gets cleaner you may be right but with coal fired stations I doubt theres a lot.

I think the cost benefit you'll really see is in the insulation, like if a house takes 25kw of heat a day to keep itself hot then thats what it takes regardless of where it comes from , but an old house might take 150kw a day so theres your new saving.

These air sourced pumps could become this decades storage heating or could turn out to be suited , the technology is still relatively new in residential. Give it a go and if it turns out that its a nightmare on power , you'd get a gas boiler in in its place handy enough, could even sell on the unit to recoup some cost.

* 25kw / 150kw are in no way representative of any building etc... its an example that you require a lot less heating in a new house.

Latro

blindside88 wrote: »

Thanks for that. Should it still be more cost effective that gas/oil to run or is the real benefit to the environment rather than my pocket?

Don't worry, I can assure you A2W is cheaper than oil with current (and most likely future) prices quite substantialy and you will not have ugly oil tank at the back.
Do you know what brand of heat pumps they are going to install?

blindside88

Latro wrote: »

Don't worry, I can assure you A2W is cheaper than oil with current (and most likely future) prices quite substantialy and you will not have ugly oil tank at the back.
Do you know what brand of heat pumps they are going to install?

I don’t know the brand yet, are there any particular brands to look out for. Some of the houses are built already so I might see can I find out the brand

Bassfish

Pardon my piggy backing on the thread, we've moved in to an A3 rated new build with a Dimplex air to water system with the oversized radiators. We moved in in June so the last few days has been the first time we've felt the need to put the heating on. There's a number of options for use such as a timer and there's an option to maintain the internal temperature at say 21c and when the temperature drops below that it kicks in. What I'm wondering is how best to use it from a cost efficiency point of view.
The house shouldn't lose heat that quickly so would the option of maintaining the temperature be a good idea of would it be better to have set times for the timer to kick in?
It's a two storey semi D about 1400sq ft.
Thanks for any tips.

Latro

blindside88 wrote: »

I don’t know the brand yet, are there any particular brands to look out for. Some of the houses are built already so I might see can I find out the brand

Any known big brand will do. They are all very similar. If one of them brings any innovation others follow immediately to keep up with the competition.

Eric Cartman

Latro wrote: »

Any known big brand will do. They are all very similar. If one of them brings any innovation others follow immediately to keep up with the competition.

This , just make sure the buolder hasnt found some cheap chinese ones or something

Latro

Bassfish wrote: »

Pardon my piggy backing on the thread, we've moved in to an A3 rated new build with a Dimplex air to water system with the oversized radiators. We moved in in June so the last few days has been the first time we've felt the need to put the heating on. There's a number of options for use such as a timer and there's an option to maintain the internal temperature at say 21c and when the temperature drops below that it kicks in. What I'm wondering is how best to use it from a cost efficiency point of view.
The house shouldn't lose heat that quickly so would the option of maintaining the temperature be a good idea of would it be better to have set times for the timer to kick in?
It's a two storey semi D about 1400sq ft.
Thanks for any tips.

Forget about thermostats. Weather compensating curve is the way to go if your device offers one. If it does experiment with the curve to achive constant 21 degrees, and let it run 24/7. There should be also setting for heating off, set it at 17 degrees external or whatever you think is best for you.

Latro

Modern inverter heat pumps modulate themselves to very low energy state if conditions allow. They dont need to be switched off at all.
For example my heat pump (9kW output) stays in 0.4-0.6 kW/hour (0.07 euro) consumption most of the time since last Thursday and my house is twice as big and not even A3 BER.

blindside88

Latro wrote: »

Modern inverter heat pumps modulate themselves to very low energy state if conditions allow. They dont need to be switched off at all.
For example my heat pump (9kW output) stays in 0.4-0.6 kW/hour (0.07 euro) consumption most of the time since last Thursday and my house is twice as big and not even A3 BER.

That’s great to hear Latro, thanks for your input. Do you find 21 degrees a comfortable temperature to keep the house at year round? Do you have any other heating source in the house also?

Bassfish

Latro wrote: »

Modern inverter heat pumps modulate themselves to very low energy state if conditions allow. They dont need to be switched off at all.
For example my heat pump (9kW output) stays in 0.4-0.6 kW/hour (0.07 euro) consumption most of the time since last Thursday and my house is twice as big and not even A3 BER.

Thanks for that, does that mean you would set it to maintain a certain temperature? I must have a play around and see can I set it to maintain a certain temp during the day and a lower one at night.

Latro

blindside88 wrote: »

That’s great to hear Latro, thanks for your input. Do you find 21 degrees a comfortable temperature to keep the house at year round? Do you have any other heating source in the house also?

I have insert stove but I used it maybe 10 days in total over 5 years.
I don't know why it is so popular, I consider it very expensive form of heating in particular if you compare to heat pump.

For me 21 in living area is perfect but for sleeping it is a bit too high.

blindside88

Latro wrote: »

I have insert stove but I used it maybe 10 days in total over 5 years.
I don't know why it is so popular, I consider it very expensive form of heating in particular if you compare to heat pump.

For me 21 in living area is perfect but for sleeping it is a bit too high.

Generally speaking do most of these systems require the same temperature throughout the house or can rooms be varied?

Latro

blindside88 wrote: »

Generally speaking do most of these systems require the same temperature throughout the house or can rooms be varied?

I have never heard of heat pump that would have separate compensating curves for separate zones. You could probably set 1 curve for whole house for 21 degrees and then have thermostat with valve to cut off bedrooms at 19-20 or instead turn down a bit UFH loops for these rooms at mainfold.

Grassey

blindside88 wrote:

Generally speaking do most of these systems require the same temperature throughout the house or can rooms be varied?

We've 3 stats 1 for each floor. Each rad in each room has a trv. Have 1st floor at 21/22, second 20, third (main bedroom) 16. Then the trv turned down a bit in other rooms as we don't use them as much so they hold the heat better.

1 thing not mentioned so far is to consider whether level pay electricity would suit you better for budgeting. Last year I didn't use it, so 20 a month during warm summer, then jumped to 150pm during the coldest parts of winter. That said, total elec for the year was about 1200. Trying level pay now this year to see if it works better on finances.

milhous

We moved in last November to a A2 rated new build with a danfoss air to water heat pump and underfloor heating. 2300sq foot. Our elec bill for everything is €200/month averaging it out. I'm not sure what costs are attributed to what. We do use the tumble dryer and washing machine daily and all other electricity costs that come with having rugrats.

Found it great last year during the poor weather, house was constant nice temp. Had it off over the summer and just put it back on, although I don't think it's running very much due to the solar gain, we a have a fair bit of glass. Not sure if any of that helps.

blindside88

Thanks everyone, great to get opinions from people that currently have a similar set up

Bassfish

Latro wrote: »

Modern inverter heat pumps modulate themselves to very low energy state if conditions allow. They dont need to be switched off at all.
For example my heat pump (9kW output) stays in 0.4-0.6 kW/hour (0.07 euro) consumption most of the time since last Thursday and my house is twice as big and not even A3 BER.

Thanks for that, does that mean you would set it to maintain a certain temperature? I must have a play around and see can I set it to maintain a certain temp during the day and a lower one at night.

Latro

Bassfish wrote: »

Thanks for that, does that mean you would set it to maintain a certain temperature? I must have a play around and see can I set it to maintain a certain temp during the day and a lower one at night.

It depends what comfort means for you. I'd probably prefer a bit cooler in the night too but I'm not here alone and you know women, the warmer the better

blindside88

Another question for those of you in the know. Is there any issue with using laminate wood floors or semi solid wood floors with ufh? I was in a shop over the weekend and they advised that there was no issue it was just down to the underlay used. Is this correct or are there wood floor types that are not suitable. I know tiles and stone would be the best conductor

Doorcase

Hi. Just looking for some help. Have air to water and underfloor heating. Guys never balanced it properly. Have 50mm liquid screed. Upstairs seems slow to heat. About 1 degree every 4 hours. I know the flow rate depends on length but do you have a gereral idea what flow rate should be in a room say 16 m squared with teo loops. Thanks. Driven demented trying to figure it out

Gumbo

Doorcase wrote: »

Hi. Just looking for some help. Have air to water and underfloor heating. Guys never balanced it properly. Have 50mm liquid screed. Upstairs seems slow to heat. About 1 degree every 4 hours. I know the flow rate depends on length but do you have a gereral idea what flow rate should be in a room say 16 m squared with teo loops. Thanks. Driven demented trying to figure it out

Who installed it? Did the contractor have a M&E consultant that you can ask for the details on your specific system?

Doorcase

self build. When working it’s great. Figured out my problem. When I run just one room the return temputure catch’s the flow temputureto quickly. The Daikin requires a delta T of 5 degrees. When I reduce my flow rate this happens even faster which is strange. Any ideas?.