UFH Heating Zone - how to do it?

[DeeNdee]

Someone probably asked this before, but I can't find it. So I am asking for your help.

I have converted a barn and installed the underfloor heating tubes a while ago. The house is upside down with the bedrooms downstairs and the living area upstairs. Downstairs there are three rooms and a hall and two bathrooms - the temperature is quite stable. Upstairs the temperature is a bit variable with the sun and the thermal mas of the underfloor heating is a little less than downstairs.

I want to install an ASHP - I've done my calculations and 7.5 to 8kW should do the job. I'm thinking one manifold for downstairs and one for upstairs and two temperature zones one on each manifold. I'm not sure how to do this and have some silly questions... Sorry!
Do I use actuators on the input of the manifolds each controlled by something. The thermostats need to talk to the heat pump as well. How does that work?
Do I actually need a buffer tank? I think I probably do, but a small one.

I'm actually quite good at normal plumbing and electrics, but I've never installed a heating system before - how hard can it be! Famous last words.

Any help would be received gratefully.

David

 

[CountryFan]

If the ufh is one zone, then wire in a motorised zone valve and thermostat

 

[DeeNdee]

Thanks for the reply, I will look up motorised zone valves and how to control them.

 

[muggles]

Exactly how you wire it in depends on what heat pump & controls you're using. Whether you need a buffer depends on system volume & resistance calculations

 

[robinbanks]

Your heat pump installlers manual should come with some diagrams of different types of install, where the filters, buffers, expansions vessel, water tank m, LLH etc go. You might also have to leave some of your loops open(uncontrolled) if the heat pump will need to pull warmth back out of them when it wants to do a defrost. I would use a loop buried in screed/other high thermal mass substrate for that function. Consult the manual

In my control setup there is a "wiring centre" that all the room thermostats link to, and there is supposed to be a set of actuators (motorised heads that slowly push valves open and closed) so that when the room thermostat calls for heat, the wiring centre opens the 3 loops that go round that room, then it also calls for heat to the heat pump. Then another room might call, and those zones open, then some time later the first one stops calling and they close..

I say "supposed to" because in the end I didn't bother with any of the valve heads; all loops stay open all the time and I just heat the screed uniformly. I also ceased bothering with the upstairs (bedroom) pipes at all, but that's another story

Because the original control plan was room-per-zone and I then switched to whole-house-is-zone I didn't bother using the room stats for control, and just use the stat built into the heat pump control unit in the hall. Whether you'll want whole house per zone depends on the construction of the house

 

[DeeNdee]

Thanks for the advice, it looks like I need to investigate "intelligent wiring centres". I want to be able to heat and cool (not as the same time!), so it gets a bit more complicated. I'm guessing there must be a box that will manage that for me.

There is no domestic hot water and only underfloor heating/cooling.

Any suggestions would be great!