Air to water

happylad

Hello,

I am think of putting in an air to water system into my house. It 3000sqr ft and has underfloor heating upstart and downstairs. It was built in 2009. Just thinking about using this as a heating system. Any recommendations or advise would be great

Merrion

There's a lot of inefficiencies in that set up - does an air-air (i.e. an inverter) not work for you?

Or - do you have enough land to put in a ground source heat pump?

I have 2 x 1kw air-to-air inverters fitted on a smaller 2 story house and it works OK. Water is heated off a standard immersion though.

Cavanjack

happylad wrote: »

Hello,

I am think of putting in an air to water system into my house. It 3000sqr ft and has underfloor heating upstart and downstairs. It was built in 2009. Just thinking about using this as a heating system. Any recommendations or advise would be great

Unless your house is insulated to the last and is airtight I think it will work out dear to run. I've it in in a new house (2 years) and find it good. The cheap oil at the minute isn't making it very attractive though.

Username John

Cavanjack wrote: »

Unless your house is insulated to the last and is airtight I think it will work out dear to run. I've it in in a new house (2 years) and find it good. The cheap oil at the minute isn't making it very attractive though.

Do you mind if I ask how much it costs to run Jack?
PM me if you like...

mycro2013

Best to use it in conjunction with solar panels and a buffer tank. Geothermal can be a bit of a miss if the pumping system is sized incorrectly as the savings are eroded by the inefficiencies of the pump.

happylad

Thanks for reply. The house has 6inch bead filled cavity, 5inches in the floor and 4inches wingspan in the ceiling along with insulated plaster board in the ceiling also. The oil is cheap alright at the moment alright.

Geothermal ground source we don't have the room. I must look at the air to air options

Cavanjack

Username John wrote: »

Do you mind if I ask how much it costs to run Jack?
PM me if you like...

Not at all. 3000sq foot house insulated to within an inch of its life. Stove lit in living area 2/3 nights a week over a mild enough winter. Constant hot water for a house full of kids and the house always warm. Total Esb bill for the year was €1700. could probably do better by setting the heat pump to run at night only and by maybe lighting the stove more often.
The jury's still out because of the high cost of installation but happy enough with the bills so far.

happylad

Cavanjack did you do airtightness on your house. Bills sound very reasonable. Is it the air to water you have with underfloor. What make of system do you have and size of heat pump.

anthony500_1

Just building a house myself at the min so I'm very interested in this also, the cost of this air tightness is outragious. The products seem to be double if not triple what they should be IMO. I'm a carpenter and I can't get over the price of the stuff. Was talking to a plumber and cousin of mine who is building as well at the min and he said if he could afford it he would go for geothermal but he can't justify double the price of the air to water unit. He also said to watch out for units that are adopted from ac units from new, as the fins in the radiator of these units are very close together and tend to frost up in the damp Irish climate causing the unit to go into defrost mode on an hourly basis drawing heat from the house, and costing money. Don't know brands etc to recommend as it was a chat we had over a bite to eat one morning

Cavanjack

happylad wrote: »

Cavanjack did you do airtightness on your house. Bills sound very reasonable. Is it the air to water you have with underfloor. What make of system do you have and size of heat pump.

16kw dimplex. Yeah done Airtightness. I think it's definitely worth it. The house is nice and comfortable. No horrible cold draughts anywher.

Water John

With a modern high, quality, insulation and airtight building, the annual heating bill will be quite low. We are talking about around €500/year.
This is what justifies doing it well. A build of this sort also needs MHRV. This again is a capital cost, but very little running cost.
OP I presume you are living in the house already, 2009 build. What is heating it at present? what is the annual bill?

Anyone using a RE source, would be totally wasting their money putting in solar panels. The ROI does not justify it.

Air to Water is fine. With the house, described above, the extra cost of Ground Source is not justified.

Who2

pv panels hooked back to the emmersion seems to be the most economical way to go at the moment. generating its own power (daylight not sunlight) and back heating water. Heat recovery unit and thermal bead with good windows surrounded by air tightness tape and youll be alright. For anyone with pre 06 built houses there are grants available that are fairly sizeable, some as far as 90%.

_Brian

As mentioned earlier the quality of detailing in the build would need to be exceptionally high for it to be a success.
These systems work on the principal of having the house super low in heat loss terms, the system then pumps in low levels of energy over time. The more heat loss and lack of air tightness in the house the less effective the overall effect of the heating as it's being lost too quickly.

An airtightness test would be essential in determining the suitability of the house for such a heating system, and my opinion is that houses need to have been built with this in mind, a standard build will perform poorly.

Muckit

Passive housing is all very well but id hate to be in a position where if somebody farted, you couldn't open a window.

_Brian

Muckit wrote: »

Passive housing is all very well but id hate to be in a position where if somebody farted, you couldn't open a window.

Why couldn't you open a window ?

J.O. Farmer

_Brian wrote: »

Why couldn't you open a window ?

The house wouldn't be very passive then?

_Brian

J.O. Farmer wrote: »

The house wouldn't be very passive then?

Ahh lads, ya can still open a window for air if ya want.
They have doors that open too.

CloughCasey1

Passive is a fad!!

_Brian

CloughCasey1 wrote: »

Passive is a fad!!

Passive is the ideal where money is no object.
But there's no reason any house build shouldn't take ideas from passive building processes to improve their subsequent performance.

Username John

_Brian wrote: »

Passive is the ideal where money is no object.
But there's no reason any house build shouldn't take ideas from passive building processes to improve their subsequent performance.

+1

We built a house about 10 years ago, and we didn't pay any heed to solar gain. In hindsight, massive mistake...

I think passive, on the right site, done right, would be a great house to have.

CloughCasey1

_Brian wrote: »

Passive is the ideal where money is no object.
But there's no reason any house build shouldn't take ideas from passive building processes to improve their subsequent performance.

Couldnt agree more. Any A3 building regs compliant new build will be 85% passive anyway. The final 15% will cost the poor punter 20-30k for an additional saving of €350-€500 per yr.

Take a typical 2 storey detached house

150-200mm Aerobord under screed
200mm pumped cavity
400mm Fibreglass in attic
TG Munster Future proof or O'Gradys comparative version
Ensure as little thermal bridging as possible
Airtightness membrane to ceiling and tape around all windows and doors. Seal top of all conduits into joists in both floors. Hopefully with all this done it will get a very positive air tightness test result

Heating option 1
Air to water running to underfloor on both floors if possible. Programmable hermistats in each room to control.
PV on roof (only if extra boost required for Part L compliance)

Heating option 2
Condensing gas or oil boiler to radiators (Do NOT use underfloor with oil or gas). Each room to have programmable stats same as the underfloor option above with PV on roof inverted into the power supply to house. (PV is cheaper than thermal solar and gives a far better push for the renewables compliance for house to meet regulations)

Secondary Heating.....ideally no secondary heating as efficiencies will never match the main heating. A nice wood burning stove with efficiency of over 75% might not drag down the compliance too much.

And seeing you now have an airtight deathtrap the most important piece of the jixsaw a heat recovery ventilation system. (Doesnt improve the BER one bit it mostly makes it worse) but its either that or sick children with inhalers.

Thats about the size of it. Anything other than all the above is a waste of your hard earned money.

Reggie.

Username John wrote: »

+1

We built a house about 10 hours ago, and we didn't pay any heed to solar gain. In hindsight, massive mistake...

I think passive, on the right site, done right, would be a great house to have.

Jaysus that didn't take long john

Water John

Casey, good resume. The only part I would quibble with is in option 2, you say, not to use a hot water source with UFH.
I disagree. Simply you an integrated mixer system that lowers the water temp going into the UFH to below 40C. Alternatively, use the hot water source to heat a cylinder and a secondary loop to the UFH with the integrated mixer.

A2W would be my first choice.
Any new house should be built to A3 standard. We ridicolously waste energy heating sub insulated, drafty houses, incl my own of 27 years.

CloughCasey1

Water John wrote: »

Casey, good resume. The only part I would quibble with is in option 2, you say, not to use a hot water source with UFH.
I disagree. Simply you an integrated mixer system that lowers the water temp going into the UFH to below 40C. Alternatively, use the hot water source to heat a cylinder and a secondary loop to the UFH with the integrated mixer.

A2W would be my first choice.
Any new house should be built to A3 standard. We ridicolously waste energy heating sub insulated, drafty houses, incl my own of 27 years.

That can be done but i was talking as much in terms of the Part L conpliance as anything else. The BER is scalded when ya match undefloor with oil or gas. Like it or not every new house will have to be an A3 from now on to even come close to meeting the regs.

Reggie.

happylad wrote: »

Hello,

I am think of putting in an air to water system into my house. It 3000sqr ft and has underfloor heating upstart and downstairs. It was built in 2009. Just thinking about using this as a heating system. Any recommendations or advise would be great

An chance you could put in the horizontal system in or have you enough room?

_Brian

Reggie. wrote: »

An chance you could put in the horizontal system in or have you enough room?

You mean the pipes buried in the garden ??

If space is a problem you can also drop a few bore holes and the pipe goes down into them.

Water John

Both of those are a bit more efficient but you would not have the ROI on the extra cost.

Reggie.

Water John wrote: »

Both of those are a bit more efficient but you would not have the ROI on the extra cost.

Explain?

Water John

The COP of ground and water to water is higher. The ground works and boreholes add to the cost. Your balancing one against the other.

As someone puts it, is their a return on achieving a passive house, costing more, than an A3 standard for a house.

The best would be water to water if one had a stream or lake near the house. If one had a good well water supply it could also be done. A COP heading for 6:1 is achievable. Don't know of anyone providing it though.

Reggie.

Water John wrote: »

The COP of ground and water to water is higher. The ground works and boreholes add to the cost. Your balancing one against the other.

As someone puts it, is their a return on achieving a passive house, costing more, than an A3 standard for a house.

The best would be water to water if one had a stream or lake near the house. If one had a good well water supply it could also be done. A COP heading for 6:1 is achievable. Don't know of anyone providing it though.

No issue here with the horizontal system. Think it cost about 2k more to install. That's about it

Water John

There is also the question of, type of ground etc. Some don't perform too good.
Fine if it works.
A while since I did figures but to my memory, ground cost a lot more than 2K extra.

Reggie.

Water John wrote: »

There is also the question of, type of ground etc. Some don't perform too good.
Fine if it works.
A while since I did figures but to my memory, ground cost a lot more than 2K extra.

Just the pipe and the digging of it was the extra for us. I think 12k was the total cost. That was 2009. A neighbour put in the air to water at 9kish around the same time

Water John

Reggie, you and I are farmers and a bit of digging and groundworks wouldn't bother either of us. In real full pricing terms, I think it would be more and the plant is dearer. Again I would have to check.
Also remember, house builds now are a higher standard, using only about €500/year for space heating. What capital spend is worth getting €100 off that?

Worse with solar panels, which save about €170/year on hot water.