The Efficient Home Forum

Hi,

I’ve got an EvoHome Y-Plan system that I installed myself. I’ve done it exactly as per the book, with a BDR91 relay on each side of the 3-port valve. Wiring in the 10-way junction box is as per page 47 of the installation guide. Initially I was thinking that at some point I might add a third relay for boiler control, but the default TPI is working fine for me anyway.
All the radiators have HR92s on them apart from the Bathrooms which have retained their TRVs. The hot water cylinder has the CS92 hot water kit fitted. The boiler is a traditional system boiler, however it’s running with an external expansion vessel in the loft rather than a tank. The pump is set to a fixed speed. I do not believe that there is an automatic bypass valve. (And yes, with most of the radiators closed it whistles a bit)

We’re looking at having the Kitchen done. Not just units but some building works too and as part of that having warm water Under Floor Heating fitted to the newly enlarged room rather than the existing HR92 radiator. The Kitchen work will be done by a local indie (not the big chains!) and they will be managing the trades.

I'm not expecting their plumber will know EvoHome, but equally I don’t know plumbing! So before speaking to their plumber I’d like to get my head around it first...

What’s the best way of adding in UFH into an existing Y-Plan system and then controlling it with EvoHome?

I'd like to do it properly and if that means additional complication in converting to S-Plan 2-port valves with automatic bypass etc then so be it - I'd rather it was done the best way than any cheap bodges.

Thanks!

When installing evohome on either an S or Y Plan system you need a bypass valve fitted... Just simply add a zone valve off the heating side for UFH if the total heating load is under 22kW or convert to S Plan Plus... Choice is yours!

Hi may I ask if you could provide a schematic? Is it possible to add the the UFH at the radiator 22mm pipe after the Y plan valve for HW and CH with radiators if both systems will start and stop at the same time?

cash365 wrote:Hi may I ask if you could provide a schematic? Is it possible to add the the UFH at the radiator 22mm pipe after the Y plan valve for HW and CH with radiators if both systems will start and stop at the same time?

This is how it should really be done...

Hi, Thank you for both reples.

May I ask you if it is possible to keep the system as it is and add a branch of UFH with a 4043 valve that would be controlled by the HCE80R? My system has already a bypass valve.

The 3x zones for UFH are two areas of 2m2 (hallway and cloackroom) and one of 10m2 (kitchen). I haven't installed any radiators yet at the kitchn and cloack room and I believe the hall radiator is a bypass radiator.

The Delta T difference is between the UFH output and return? I understand that the quicker the water travels the lower the Delta T difference at least from what I remeber in physics.

Apologies if you are going to repeat yourself I manged to read up to 2018 post and I saw that I cannot zone the UFH and radiator in one zone as they are different systems. Wonder if there is any firmware update for Evohome that could overcome that.

Kind regards,

Kyriakos