ASHP in a new build - any advice, dos or donts to a complete newbie

[Fallowfields]

House will be a 1585 sqft brick and tile with 150mm insulation. We are thinking UFH. Where to put the unit outside, N, S, E, W. Where the hell did you put the internal controls and can it be put in a  larger tall kitchen cupboard to fit in with the rest of the units. 

 

TIA

 

FF☺️ 

[JohnMo]

15 minutes ago, Fallowfields said:

House will be a 1585 sqft brick and tile with 150mm insulation. We are thinking UFH. Where to put the unit outside, N, S, E, W. Where the hell did you put the internal controls and can it be put in a  larger tall kitchen cupboard to fit in with the rest of the units. 

 

TIA

 

FF☺️ 

 

UFH as a single zone on ground floor and any upstairs bedrooms. Consider fan coils if you need cooling upstairs. Other provision for electric panel heater in bedrooms (don't buy until after you know you need them). Electric towel rads in wet rooms.

 

Make sure you have decent heat loss calculations before going any further. Ideally do them yourself so you know what's what.

 

You don't want the sun shining on the ASHP, ignore any advice that says otherwise. Sun will mess up the heat sensor reading.

 

Indoor controls depends on unit being installed. Many will have an internal thermostat so really needs to in the living space not in a cupboard. They are just like a thermostat. Only consider a monobloc ASHP so everything is outside except a small controller.

 

Don't do any 3rd party controls.

 

Single zone means no thermostats other than the one in your controller, no actuators on the manifold, no need for a mixer or pump on the UFH manifold. Most likely no need need for a buffer or volumiser. 

 

Using a Government Grant for the free £7500. I didn't bother was too expensive, so just bought it all myself. Installers just want to rip you off.

[elite]

The outdoor units will have specs of how much space required around them. I don't think N, S, E, W will have a big impact so go with wherever it will be least annoying athestically and acousticly (e.g. don't put next to bedroom window), and factor in pipe runs.  Are you having an unvented cylinder for hot water? I would go with a plant room (large cupboard) to house UVC, UFH manifold and controls

[Fallowfields]

5 minutes ago, JohnMo said:

 

UFH as a single zone on ground floor and any upstairs bedrooms. Consider fan coils if you need cooling upstairs. Other provision for electric panel heater in bedrooms (don't buy until after you know you need them). Electric towel rads in wet rooms.

 

Make sure you have decent heat loss calculations before going any further. Ideally do them yourself so you know what's what.

 

You don't want the sun shining on the ASHP, ignore any advice that says otherwise. Sun will mess up the heat sensor reading.

 

Indoor controls depends on unit being installed. Many will have an internal thermostat so really needs to in the living space not in a cupboard. They are just like a thermostat. Only consider a monobloc ASHP so everything is outside except a small controller.

 

Don't do any 3rd party controls.

 

Single zone means no thermostats other than the one in your controller, no actuators on the manifold, no need for a mixer or pump on the UFH manifold. Most likely no need need for a buffer or volumiser. 

 

Using a Government Grant for the free £7500. I didn't bother was too expensive, so just bought it all myself. Installers just want to rip you off.

Thank You, yes I had heard placing the unit on the warmer wall was the way to go, so thankyou for your direction on that. Clear and concise, many thanks FF☺️

[Fallowfields]

8 minutes ago, elite said:

The outdoor units will have specs of how much space required around them. I don't think N, S, E, W will have a big impact so go with wherever it will be least annoying athestically and acousticly (e.g. don't put next to bedroom window), and factor in pipe runs.  Are you having an unvented cylinder for hot water? I would go with a plant room (large cupboard) to house UVC, UFH manifold and controls

Eek large cupboard, there goes my utility I dreamed of. Damn planning, they wouldnt give us a garage and now we have to find space in the house. Crazily, we are trusting a local plumber to advise us as we seriously are clueless so no idea about unvented cylinder at this point. 😫

[JohnMo]

My Maxa heat pump doesn't have an indoor controller, everything is on the outside unit. I use a thermostat to switch between cooling and heating.

 

Maxa now selling in the UK. Available in R32 and R290 (R290 is flammable so has placement restrictions). But for ease of use and setup I would seriously consider Panasonic.

 

Heat pump generate low temp water for DHW (max around 50 Deg) so 3 bed house needs 210L plus. The cylinder can be horizontal or vertical, could you locate in loft for example?

[Bancroft]

1 hour ago, JohnMo said:

 

UFH as a single zone on ground floor and any upstairs bedrooms. Consider fan coils if you need cooling upstairs. Other provision for electric panel heater in bedrooms (don't buy until after you know you need them). Electric towel rads in wet rooms.

 

Make sure you have decent heat loss calculations before going any further. Ideally do them yourself so you know what's what.

 

You don't want the sun shining on the ASHP, ignore any advice that says otherwise. Sun will mess up the heat sensor reading.

 

Indoor controls depends on unit being installed. Many will have an internal thermostat so really needs to in the living space not in a cupboard. They are just like a thermostat. Only consider a monobloc ASHP so everything is outside except a small controller.

 

Don't do any 3rd party controls.

 

Single zone means no thermostats other than the one in your controller, no actuators on the manifold, no need for a mixer or pump on the UFH manifold. Most likely no need need for a buffer or volumiser. 

 

Using a Government Grant for the free £7500. I didn't bother was too expensive, so just bought it all myself. Installers just want to rip you off.

 

What are the downsides of only having a single zone?

[Fallowfields]

1 hour ago, JohnMo said:

My Maxa heat pump doesn't have an indoor controller, everything is on the outside unit. I use a thermostat to switch between cooling and heating.

 

Maxa now selling in the UK. Available in R32 and R290 (R290 is flammable so has placement restrictions). But for ease of use and setup I would seriously consider Panasonic.

 

Heat pump generate low temp water for DHW (max around 50 Deg) so 3 bed house needs 210L plus. The cylinder can be horizontal or vertical, could you locate in loft for example?

Thank you that is useful, will have a look. Good old planning deprived us again of any decent roof space bringing us to a 1.5 storey, will have to check with the other half as to what space there could be up there. FF😊

[JohnMo]

1 hour ago, Bancroft said:

What are the downsides of only having a single zone?

None really, you balance the flows to get the room temperature you want. You get rid of a buffer that comes with zones, so you end up with a better CoP (lower running costs). Your install is minimal so costs less in useless equipment. 

[G and J]

4 hours ago, JohnMo said:

I use a thermostat to switch between cooling and heating.

What stat are you using?

[JohnMo]

A Computherm Q20RF set to 1.0 hysterisis, so that gives +/-1 Deg either side of asset point. Currently set to 21, so at 20 heat comes on and at 22 cooling comes on. But I am thinking the control is too fine so a simple switch (heat cool) may be easier and use the thermostat to give a remote on off. Still a bit of a thought process 

[G and J]

So it presents different connections for above and below set point, and you use that to switch between heat and cooling mode.

 

If so, in winter if you light your woodburner (you might have to instal said woodburner first), the system could then go into cool mode.  

[JohnMo]

22 minutes ago, G and J said:

So it presents different connections for above and below set point, and you use that to switch between heat and cooling mode.

 

If so, in winter if you light your woodburner (you might have to instal said woodburner first), the system could then go into cool mode.  

The thermostat can be configured to work in either cool or heat mode. Just a couple of buttons pushes.

 

My worry with current configuration, is in heating mode I get some solar gain or light the fire or have the WC not quite right and the cooling switches on, not the best for efficiency.

[JohnMo]

28 minutes ago, JohnMo said:

The thermostat can be configured to work in either cool or heat mode. Just a couple of buttons pushes.

 

My worry with current configuration, is in heating mode I get some solar gain or light the fire or have the WC not quite right and the cooling switches on, not the best for efficiency.

Well after writing the above, I moved the thermostat to control remote on and off, (set 0.1 hysterisis to stop overshoot if flow temp needs to be controlled) and added a switch to move between heating and cooling.

[G and J]

3 hours ago, JohnMo said:

Well after writing the above, I moved the thermostat to control remote on and off, (set 0.1 hysterisis to stop overshoot if flow temp needs to be controlled) and added a switch to move between heating and cooling.

I’ve that ‘I’m being dumb’ feeling but please could I see a circuit diagram of the above. 

[Dave Jones]

1. do heatloss calcs . 

2. you need a largish cupboard to store the cylinder, pipework etc. forget any kitchen units.

3, make sure you are airtight, that means no trickle vents etc or it will cost a fortune to run.

[scottishjohn]

On 20/08/2024 at 13:52, JohnMo said:

The cylinder can be horizontal or vertical, could you locate in loft for example?

Iwould avoid a horizontal clyinder if possible --will make bleeding from system al ot harder 

and if you must have one make sure its not exactly hoorizontal --have a high end so air will go to it and hopefully not get trapped

[ReedRichards]

There has been recent publicity about a hot water unit that really would fit inside a large kitchen cupboard.  See 

  But it's very much untested in real domestic settings, so far.

[ReedRichards]

On 20/08/2024 at 14:39, Bancroft said:

 

What are the downsides of only having a single zone?

 

If you want all the rooms in the house to be at the same temperature 24/7 there are no downsides.  

[AartWessels]

On 23/08/2024 at 08:20, ReedRichards said:

 

If you want all the rooms in the house to be at the same temperature 24/7 there are no downsides.  

Which will happen in an airtight house with mvhr anyway. 

[G and J]

46 minutes ago, AartWessels said:

Which will happen in an airtight house with mvhr anyway. 

I have read on here many times that in cooler months upstairs bedrooms run a couple of degrees cooler than downstairs with what appears to be almost standard running setup of MVHR, ASHP, single zone UFH downstairs, no heating upstairs, decent level insulation.

 

MVHR doesn’t, it appears, force all rooms to the same temperature as it simply doesn’t move enough air round to achieve that.  That’s why it’s not the useful for cooling.  It might distribute heat a bit, but not enough to equalise.  
 

Given that lower upstairs temperature I think the super simplicity of that setup is very attractive.

[ProDave]

On 20/08/2024 at 13:32, elite said:

The outdoor units will have specs of how much space required around them. I don't think N, S, E, W will have a big impact so go with wherever it will be least annoying athestically and acousticly (e.g. don't put next to bedroom window), and factor in pipe runs.  Are you having an unvented cylinder for hot water? I would go with a plant room (large cupboard) to house UVC, UFH manifold and controls

Our ASHP is on the south facing wall, almost by accident as that is the best place for it at the back of the house.  But in winter on a cold still sunny day, the front of the house can retain frost all day due to no sun and little air movement, while the back of the house is frost free and can actually feel warm in the sun.  I refuse to believe the ASHP is not better off there than on the north frosty side of the house.

 

Re "plant rooms" I don't have one.  What was supposed to be the plant room is now my office / workshop.  It has the MVHR unit and some plumbing controls and a pump.  That is it.  the hot water tank got moved out to a far more sensible central location to optimise short hot water pipe runs to the points of use, that is in a cupboard in the corner of the spare bedroom.  Consumer unit is in the utility room. on the wall.  all network and AV stuff in the cupboard under the stairs.

 

If space is tight, I recommend distributed services like that sited in the best place for each, rather than one plant room full of stuff which (from what I have seen) often puts things like hot water tanks of far from optimum places.

[saveasteading]

12 minutes ago, ProDave said:

refuse to believe the ASHP is not better off there than on the north frosty side of the house.

It will be better but not a lot. 

The amount of air pumped will soon exceed any affected by the cold surfaces.

 

I did have a job where the original architect put solar panels next to a north facing wall though.

[joe90]

My ASHP was on a west wall, it frosted up occasionally but never in the afternoon with the sun shining.

[mjc55]

On 23/08/2024 at 08:20, ReedRichards said:

 

If you want all the rooms in the house to be at the same temperature 24/7 there are no downsides.  

 

But would you want all rooms to be at the same temperature?

 

I am just thinking about UFH and looking at different zones (very early in the process so open to anything).

 

So would you want a bedroom to be the same temperature as a large kitchen/diner/lounge area or the same as a TV room?  This is where I don't quite understand how it would work!

 

I suppose our natural flow (us not the UFH!) would be from bedroom to kitchen/diner area to diner/lounge area during the day (with occasional trips to the loo).  Back to the kitchen/diner area later, on to the TV room late on and finally back to the bedroom.  There would be two spare bedrooms - although one would be for office/sewing etc functionality.  We would probably want to keep the utility room a bit cooler (food etc.)

 

So how would this work as a single zone? 

 

Obviously in a house that is near to passive as we can get it, it could be said that the UFH would hardly be needed.  And we are also planning for a wood burning stove in the lounge area.  One other thing to factor in is that we are fresh air fiends - we ALWAYS sleep with a window open (I do accept that this practice could possibly change in the new house) and we plan to have a lot of glass at the back (West) of the house and would, in all likelihood have this open in the afternoon.

 

So, would the one-zone solution work given that?