Heat pump size

L.Demps

Hi all,

We have been quoted two different size heat pumps and two different loop sizes from two different installers and just not sure which to believe. We don't want to underside the heat pump but not over size it either.
The house is 215m squared. Very high levels of insulation, air tightness and MHRV.

Our soil is very marley. Depending on who you talk to not ideal/ideal for geothermal. We are thinking of filling the trenches back up with topsoil that we took out when digging our v long laneway to compensate for this.

Both are quoting for the danfoss ground source heat pump DHP-H Opti Pro.

Installer 1: 6kw heat pump with 300m loop in the ground.

Installer 2: 9kw heat pump with 600m loop in the ground.

Anyone have any idea what size heat pump we should be going for? Thanks. L.Demps

BryanF

whats the houses kwh/m2/yr ?
whats the expected heat load for an average day in winter?
what is your architect or heating engineer suggesting it will be?

Condenser

L.Demps wrote: »

Hi all,

We have been quoted two different size heat pumps and two different loop sizes from two different installers and just not sure which to believe. We don't want to underside the heat pump but not over size it either.
The house is 215m squared. Very high levels of insulation, air tightness and MHRV.

Our soil is very marley. Depending on who you talk to not ideal/ideal for geothermal. We are thinking of filling the trenches back up with topsoil that we took out when digging our v long laneway to compensate for this.

Both are quoting for the danfoss ground source heat pump DHP-H Opti Pro.

Installer 1: 6kw heat pump with 300m loop in the ground.

Installer 2: 9kw heat pump with 600m loop in the ground.

Anyone have any idea what size heat pump we should be going for? Thanks. L.Demps

I wouldn't put a ground collector in marl. Very high risk of freezing the ground. Adding top soil won't change this as it will become the same as the surrounding ground in a short space of time. You should really consider a vertical bore.


Your heatloss will determine which heat pump you need but 9kw is on the high side for a house of that size meeting current regs. How hot water is produced will have an affect on how much leeway you'll allow in sizing however.

L.Demps

Hi Condensor,
A few of our neighbours with similar soil have installed this same system and are happy with it so we're going to give it a go.
We're not using solar panels for hot water and the heatpump has a 180l dhw storage tank integrated.
L. Demps

Condenser

L.Demps wrote: »

Hi Condensor,
A few of our neighbours with similar soil have installed this same system and are happy with it so we're going to give it a go.
We're not using solar panels for hot water and the heatpump has a 180l dhw storage tank integrated.
L. Demps

In that case i'd go with the larger unit. Provided the collector is 50% bigger than the smaller unit it will have less running hours so less demand on poor ground and the hot water cylinder is very small so you'll have alot of cycling of the heat pump on that also.

L.Demps

Do you think we'd be better going with a bigger water tank, think the next one up is 300l.

Thanks.

Condenser

L.Demps wrote: »

Do you think we'd be better going with a bigger water tank, think the next one up is 300l.

Thanks.

Heat pumps shouldn't work past 50C regardless what various manufacturers claim. It places immense strain on the equipment and shortens the life span. You won't get much use off 180L of water at 50C so your immersion will need to be constantly on just to top the water up to 65C.
TBH if your suppliers aren't informing you of this stuff I suggest you find another supplier because its pretty basic info you should be given.

JD6910

sounds like your ground conditions are dodgy!! if in doubt dont take a chance.

Your heat demand will be very small if your insulation and airtightness is correct. with a small heat demand - pop in a boiler and solar and a stove. you wont need heat in that house if it is insulated correctly!!! you can then rest easy and not worry about ground conditions etc.... also any plumber can fix and maintain your system and you wont be part of the bad news stories on these forums......best of luck with the decision.

L.Demps

Hi Condensor, yes our installer did tell us about that. We are happy with him and happy to go with that system.

L.Demps

Hi JD6910, I know it will take very little to heat our house but I believe a heap pump and UFH is the way forward. I believe in future proofing the build and I think that heat pumps are the future. I've given much thought to all the options available to me and have decided to go down this route. Hope I'm making the right decision, ask me in ten years!
Thanks, L. Demps.

JD6910

L.Demps wrote: »

Hi JD6910, I know it will take very little to heat our house but I believe a heap pump and UFH is the way forward. I believe in future proofing the build and I think that heat pumps are the future. I've given much thought to all the options available to me and have decided to go down this route. Hope I'm making the right decision, ask me in ten years!
Thanks, L. Demps.

yep your prob right. i was just scared of all the stories on here. i still reckon you can beat the tried and tested systems, easy to fix, low capital costs etc... i found trying to get independent advice impossible. everyone is on the sell!!!!
alot of your decision should be based on how ye live. if you are in the house all day they yep a HP is prob best. if you out all day, id argue a boiler and timeclock is better and you decide when you want heat etc... best of luck.