UFH in existing Evohome system Y planned open vented

[cash365]

Good morning from the North East. I have a renovation going on my ground floor and would like to add UFH along with radiator I have in the ground floor (concrete suspended beams) which will have an approx 14m2 area with tiles that needs the UFH. The UFH will be devided in 3 zones with two 2m2 areas and one 10m2.

My questions are the following:

1) Can I install the 22mm pipe after the existing T valve of my Y system or does iit need to come before that? The reason I ask is because the UFH and radiators will work the same hours simutaneously.

2) Could I set the radiator and UFH zone under one bigger zone area?

3) Lastly should I leave current Y valve to the BDR91 and set the valve for the UFH manifold to the HCE80R?

Many thanks for your help.

PS tried to find an answer before posting and saw that this could be done in systems less than 15m2 area in some previous posts.

[Richard]

Good morning from the North East. I have a renovation going on my ground floor and would like to add UFH along with radiator I have in the ground floor (concrete suspended beams) which will have an approx 14m2 area with tiles that needs the UFH. The UFH will be devided in 3 zones with two 2m2 areas and one 10m2.

My questions are the following:

1) Can I install the 22mm pipe after the existing T valve of my Y system or does iit need to come before that? The reason I ask is because the UFH and radiators will work the same hours simutaneously.

2) Could I set the radiator and UFH zone under one bigger zone area?

3) Lastly should I leave current Y valve to the BDR91 and set the valve for the UFH manifold to the HCE80R?

Many thanks for your help.

PS tried to find an answer before posting and saw that this could be done in systems less than 15m2 area in some previous posts.

If adding to an existing system, you need to ensure you have enough capacity through the pipework and the existing 3 port valve without too much pressure drop to satisfy the new flow rate including the UFH. In theory 22mm can supply approximately 23kW at a temp difference of DT20, but far more calculations are required, as the UFH system won't be DT20 (probably DT7 which requires nearly 4x the flow rate).

Each zone needs to be controlled correctly, so normally you would install a system like this as per the evohome installation guide page 46 schematic, but you would have the UFH tee'd off with a separate zone valve operated by the HCC80R/HCC100 and HR91/HR92 on all rads without a zone valve.

You don't normally design rooms/zones to have radiators and UFH in the same room/zone and there is no option on evohome to do this. Creating two zones in the same room is not recommended.