GSHP settings and thermostat questions

devm

Hello,

I have just moved into a house with a GSHP and UFH and wanted to understand the temperature controls and thermostat settings better.

I have an option on the heat pump settings to control the room temperature (currently set at 24.1). The rooms in the house all have dial thermostats and are mostly set to 21. How does the pump room temp setting influence or affect the actual room temperature? Is the pump room temp set slightly higher than the required room temp to allow for heat loss from water moving from the UFH cylinder to the room?

As the rooms have dial thermostats can I replace them with digital ones to give me more control over the room heating. For example, some rooms will only get used on the weekends so I would be keen for these rooms to be kept cooler Monday to Friday (I guess at the set back temperature) and for them to them increase to 21 degrees on weekends.

Grateful for any advice. Thanks.

matelodave

Underfloor heating is usually distributed through loops controlled by actuators which in turn are controlled by the room thermostats which again may or may not control the circulating pump(s)., so you really need to check how your system is configured.

There's no reason why you should not change dial type thermostats to digital or even programmable stats, but again you need to understand how they are wired, especially if you want to change to wireless stats.

We originally had programmable stats in each room and I tried for months to get them tweaked to keep the place warm at the times we wanted to be warm. All that happened was that the system cycled a lot, rooms got cold and then took ages to warm up and the energy consumption was a lot higher because the unit wasn't running at anywhere near optimum efficiency.

I have now removed all the actuators on my system and disconnected all the stats so all the loops are now open and I let weather compensation control the house temp. There is just one room stat in the coldest room used as an upper limit stat.
This makes the house much more comfortable and, as well as reducing system cycling, it also means that the house doesn't cool down as much as before and we use less electricity.

You'll probably find that underfloor heating (especially that which is buried in the subfloor) is pretty slow to respond - like a storage heater and even slower if you are running at low flow temperatures. Slow response and low flow temps means it takes ages to reheat a room if you let it get cold (our record took two days to reheat the place when we turned it right down when we went away one Christmas) so be careful that you don't turn it down too far or remember to start reheating the day before you want the room warm.

TBH I think I'd leave it alone and see how it performs perhaps making a few measurements and minor tweaks to see how the system behaves. Make sure you record any adjustments so you can revert back if you muck it up. and give the system a day or two to settle between tweaks.

Spending lots of money on posh thermostats, especially on a system with a very slow response time may well be false economy and could even increase your energy consumption if it upsets the system efficiency by making it work harder to reheat the place.