Hot Water Cylinder options

creedp

I have a geothermal heat pump with UFH throughout house and will shortly be installing DHW cylinder. I wil have a pressurized unvented system. My builder is proposing to install a twin coil 300l stainless steel cylinder (e.g. Ariston) while the HP guy was suggesting installing a single coil option (for solar if installed at future date) and connecting the HP to cylinder using a heat exchanger. Alternatively he said if I wasn't going to install ST in future just go with the single coil option and forget the heat exchanger.

I'd like some advice on even though ST is not normally installed with a HP would it be worthwhile to provide for installing this option in the future and if so would I be better off going with a dual coil cylinder or the single coil one and an external heat exchanger for the HP? I'm a bit concerned with the heat loos associated with the exchanger and maybe another option would be to install a single coil cylinder now and if I opt for solar in future I could then retrofit a heat exchanger for the HP.

If just going with pump for now is a single coil or double coil cylinder more efficient?

Thanks

creedp

creedp wrote: »

I have a geothermal heat pump with UFH throughout house and will shortly be installing DHW cylinder. I wil have a pressurized unvented system. My builder is proposing to install a twin coil 300l stainless steel cylinder (e.g. Ariston) while the HP guy was suggesting installing a single coil option (for solar if installed at future date) and connecting the HP to cylinder using a heat exchanger. Alternatively he said if I wasn't going to install ST in future just go with the single coil option and forget the heat exchanger.

I'd like some advice on even though ST is not normally installed with a HP would it be worthwhile to provide for installing this option in the future and if so would I be better off going with a dual coil cylinder or the single coil one and an external heat exchanger for the HP? I'm a bit concerned with the heat loos associated with the exchanger and maybe another option would be to install a single coil cylinder now and if I opt for solar in future I could then retrofit a heat exchanger for the HP.

If just going with pump for now is a single coil or double coil cylinder more efficient?

Thanks

Sorry to be doing this but would be very interested in anyone's views on this. Is seems the HP supplier likes to use the external plate exchanges because it has a large coil area, approx 2m2, as against the 0.79m2 for the top coil of a 300l dual coil cylinder. He did offer to connect the HP to both coils in the dual cylinder which would increase the total coil area to approx 1.6m2. He said the large the coil size the more efficinet the HP will be as heating up the water.

Thanks

slavetothegrind

it depends really on why?

does he want a really fast recovery time?

what is the cost of the plate exchanger arrangement?

i would imagine it is significantly more than the extra coil in the cylinder.

i would be asking for recovery times with both options and seeing if the dual coil (linked) is sufficient for your realistic needs.

you can get triple coil cylinders leaving you one coil for future solar.

creedp

slavetothegrind wrote: »

it depends really on why?

does he want a really fast recovery time?

what is the cost of the plate exchanger arrangement?

i would imagine it is significantly more than the extra coil in the cylinder.

i would be asking for recovery times with both options and seeing if the dual coil (linked) is sufficient for your realistic needs.

you can get triple coil cylinders leaving you one coil for future solar.

I'm afraid I don't have the technical details only that the faster the recovery time the better ensuring water can be heated up at night and the faster the receovery time the less time the HP will have to operate at 50c therefore reducing strain on the HP. I know this is all very much finger in the air stuff but I though this part of the job was straight forward, i.e. the HP guy would install or recommend the installation that best suited the HP so I didn't give it any thought.

He said the plate exchange would cost €60 and he usually installs them when the client is also going with solar. Its just now that Im not initially installing solar he is asking if I would be happy to go with a dual coil cylinder or even a single coil cylinder if I don't intend installing solar in the future.

Has anyone installed an external plate exchanger and have any views on whether a dual/triple coil cylinder would be a better option?

I'll check out the triple coil cylinders which would allow the HP to be linked to 2 coils and still leave the option of connecting solar in the future.

Thanks for your help

How are going to heat the cylinder to over 60c to help prevent legionnaires disease.

creedp

gary71 wrote: »

How are going to heat the cylinder to over 60c to help prevent legionnaires disease.

The only way at moment is with immersion which will be set to boost temp of cylinder from 50c to 60c on at preset intervals.