To TRV or not to TRV

[HughF]

I was googling what sort of control strategy I'd need if I shifted to an ASHP, my googling has led me to think that full weather comp, heating on 24/7 (which is fine, as the house is occupied almost 24/7 anyway), and the odd TRV to limit room temperature if required.

 

Talking of TRVs - google brought up the ttached interesting article from back in 2011 by the EST. A little out of date (it mentions that most heat pumps are fixed speed, not inverter driven, which is now not the case).

 

Sharing here in case it's of interest.

3531-effect-radiator-valves-heat-pump-perf.pdf

[JohnMo]

You need to balance the system well, but I would try to limit them as much as possible.  Possibly bedrooms only.  The basis of the article will still hold true, with modulation, you have a little more room for error.

 

Then work out your system capacity, with those radiators with trv closed and make sure you either have a buffer big enough to cope.  Problem is anything warmer than design, the end of the modulation range can still be too large a capacity for demand.

 

Take a look at heatgeek.co.uk also, which has a few good write ups on system balance and how to best operate weather compensation.

[HughF]

10 hours ago, JohnMo said:

You need to balance the system well, but I would try to limit them as much as possible.  Possibly bedrooms only.  The basis of the article will still hold true, with modulation, you have a little more room for error.

 

Then work out your system capacity, with those radiators with trv closed and make sure you either have a buffer big enough to cope.  Problem is anything warmer than design, the end of the modulation range can still be too large a capacity for demand.

 

Take a look at heatgeek.co.uk also, which has a few good write ups on system balance and how to best operate weather compensation.

Depending on whether I have the space in a cupboard, or not, I was going to manifold the rads and balance them there. Originally the plan was to put wired actuator heads there (when I was considering a high temp system).

 

We tend to have all the doors permanently open between rooms in this house, which would make TRVs pretty redundant, would it not? 

 

if I end up having to do everything under the floorboards then I’ll just do the usual plumbing setup with a bucket of Ts

[TW9]

You're right, if you leave the doors open there's no point in using TRVs. In fact it can reduce your heat pump efficiency. Heat Geek explain why in one of their YouTube videos.