how to run towel radiators and normal radiators pipework to the ashp

[darrenkeighley]

We wish to run the upstairs radiators and the towel radiators (on different floors) on a separate feed from the ufh which will probably be run from 2 manifolds , 1 basement 50m2 and ground floor at around 90m2 .

The external walls are insulated to a U value of 0.14 roof to 0.14 and floors to 0.12 so quite good and air tightness to around 4m3/hm2

Its a new build with basement build up of 250mm pir with 300mm concrete then 70mm pir and 80mm screed over pipework 

Ground floor is block and beam 50mm pir and 70mm screed over pipework .

I would like to know thoughts on the ufh system to use and have a few questions before i ask for quotes for supply only.

 

1. Would 200mm centres be ok overall with a bit less in the bathroom at basement level .

2. Could i place the manifolds at basement level ,1 floor and 1 ceiling or will the ceiling one be better at low level on the ground floor above that it will supply.

3. I may not need the radiators upstairs so should i fit a valve and thermostat for the control.

4. The radiators are piped in 22mm pex pipe , do i connect directly to the heat pump and let the valve turn it on if needed

5. The 3 towel rails (2 first floor 1 basement) would need to be on a timed circuit and on when no normal heating is needed in summer how have you connected this to the heat pump. these are also in 22mm pex.? 

 

Thanks in advance for your replies . 

[Thorfun]

we just put electric towel radiators and ufh in our upstairs bathrooms. i thought it a massive faff to mess about with multiple circuits off the ASHP and to run all the pipework upstairs just to run the towel rads for an hour a day and the ufh for a few hours a day.

[JohnMo]

No fan of PEX piping, the coupling seem to be awfully restrictive.  Just use Hep2O, easy to get hold of locally. Piping size depends on pipe run length and number of unions

 

57 minutes ago, darrenkeighley said:

Its a new build with basement build up of 250mm pir with 300mm concrete then 70mm pir and 80mm screed over pipework 

Seems an expensive way to do a floor, just have pipes in the 250mm concrete attach to the top layer of rebar then dump the 70mm PIR and 80mm screed.

 

I would do

Electric only towel rails in bathrooms

UFH in bathrooms at 100 to 150mm centres depending on floor space available

UFH in rest of spaces 200mm sounds fine, but I would design it to match heat loss for ease of balancing

1 hour ago, darrenkeighley said:

2. Could i place the manifolds at basement level ,1 floor and 1 ceiling or will the ceiling one be better at low level on the ground floor above that it will supply.

I would have one manifold for each floor

1 hour ago, darrenkeighley said:

3. I may not need the radiators upstairs so should i fit a valve and thermostat for the control.

Is this a basement plus ground floor or do you have a second floor as well? You really should design what is needed now, making big changes once house is built is a pain. Design things, UFH and radiators to match room losses then do you need a thermostat - thermostats I would only do wireless, then you can move them if position is wrong. But aim for a fully open single zone system, otherwise you start to drive yourself towards buffers, which cost you money to buy and can hit efficiency for ever more

1 hour ago, darrenkeighley said:

4. The radiators are piped in 22mm pex pipe , do i connect directly to the heat pump and let the valve turn it on if needed

Again design the system as whole - are radiators at the same design temp as the UFH, if not mixers are needed and that changes design needs

1 hour ago, darrenkeighley said:

5. The 3 towel rails (2 first floor 1 basement) would need to be on a timed circuit and on when no normal heating is needed in summer how have you connected this to the heat pump. these are also in 22mm pex.? 

Just do direct electric, then you can run cooling if need from ASHP and have warm towels

 

[darrenkeighley]

Nearly all the pipework is now in . Just the manifolds to add and then attach the upstairs radiators and bathroom towel rads. 

May as well pipe the rest as we need the ceiling up. I can move the main manifold to a kitchen unit to keep it on the same level.

We want to run on weather compensation and have been advised an ecodan 8.5kw  .

[JohnMo]

3 minutes ago, darrenkeighley said:

ecodan 8.5kw 

Sounds massive for a new build - get them to do an 8kW. It's a very different machine and way more flexible. It has 2x compressors instead of the normal one; a 2kW and 6kW in a single case.  So super flexible.and good modulation.

[darrenkeighley]

21 minutes ago, JohnMo said:

Sounds massive for a new build - get them to do an 8kW. It's a very different machine and way more flexible. It has 2x compressors instead of the normal one; a 2kW and 6kW in a single case.  So super flexible.and good modulation.

Thanks for that i will have a look as we have not ordered yet . no electric supply yet