A2W UFH and thermostat zones

ec_pc

All,

I have a question regarding thermostat heating zones in a 2 story house with A2W heat pump, UFH heating downstairs and rads upstairs. House is being renovated and first fix elec and plumbing is almost complete.

During original walk through of plumbing etc it was agreed to have multiple thermostat controlled zones but since that plumber has come back to say as A2W is always on that multiple zones are not needed and 1 is sufficient.

Sparks are not in agreement and I can't understand the logic.

Any thoughts / advice? I believe we need multiple zones to control heating especially during summer.

Calahonda52

of course you need different zones

exaisle

Calahonda52 wrote: »

of course you need different zones

I think the question is...how many? I'd be inclined to go with just 2...upstairs and downstairs. I was advised by the guy who services/repairs heat pump to minimise the number of zones as having multiple zones will cause the heatpump to switch on and off far more frequently and that this will shorten the life of the compressor significantly. Having changed from multiple zones to just 1(i live in a bungalow) i havent noticed any increase in my energy bills.

Calahonda52

exaisle wrote: »

I think the question is...how many? I'd be inclined to go with just 2...upstairs and downstairs. I was advised by the guy who services/repairs heat pump to minimise the number of zones as having multiple zones will cause the heatpump to switch on and off far more frequently and that this will shorten the life of the compressor significantly. Having changed from multiple zones to just 1(i live in a bungalow) i havent noticed any increase in my energy bills.

The reduced cycling is also achieved by using a buffer tank. Not widely used here in Ireland but an essential component IMO

hatchman

A quick question on the mechanics on why a compressor starting and stopping repeatedly shortens it lifespan ? Would it not just wear the same irrespective of the number of starts rather than pure running time ?

tedimc

exaisle wrote: »

I think the question is...how many? I'd be inclined to go with just 2...upstairs and downstairs. I was advised by the guy who services/repairs heat pump to minimise the number of zones as having multiple zones will cause the heatpump to switch on and off far more frequently and that this will shorten the life of the compressor significantly. Having changed from multiple zones to just 1(i live in a bungalow) i havent noticed any increase in my energy bills.

I was advised the same - regarding a GSHP. Our system isn't zoned (bungalow) and I find it fine in terms of cost and comfort.

My mother's house has individually zoned rooms on Oil UFH. Looking back, I think it was a mistake as the heat travels from room to room anyway. Convenient for turning the heat off in spare bedrooms, but that's probably not something you should do anyway for an extended period of time.

I'd stick to the two zones at a max. Likely your heat will travel upwards anyway, so you may have limited call for heat upstairs.

If it was rads, I would say individual zoned rooms, but the water temp for AS & GS is a lot lower than rads.

rampantbunny

OP, do you/will you have MHRV installed?
With MHRV installed there's even more reason to minimize the number of zones. Even though mechanical heat recovery ventilation is not a heating system it does duct heat from one place to another. Over a period of time, this helps equalize the temps across all rooms (unless of course you are leaving windows open ..which defeats the whole MHRV ideal).
My house has a single zone for both upstairs and ground floor. When system was set up, the installer simply reduced the flow of UFH to the upstairs rooms via the manifold valves. This is a low-tech approach but rooms upstairs are always a degree or two below ground floor which is what you would normally want. Would have preferred to have an upstairs zone but I don't miss not having it TBH.