Ufh manifold, blending valve with ASHP.

[ectoplasmosis]

On 14/07/2024 at 08:26, JohnMo said:

It's just an adjustable blending valve, you are only altering the amount of return water that gets mixed into supply water. They aren't the best mixer. They generally will always drop the temperature of the supply by around 10 degs or more. So if your max supply is 45 degs you will get somewhere around 35 degs in the floor.

 

Really depends on the difference in design temp of the floor compared to radiators and also the floor buildup.

 

If you need to blend electronic (ESBE) controlled by your Vaillant controller would be best. But at full retail prices - ouch not cheap. A mechanical solution would be an Ivar mixer that will control to exact temperatures and is very adjustable.

 

 

Thank you, very detailed and helpful.

 

We don't have much time nor money left over to change anything right now. Will our current setup, with the Reliance HEAT970366, be OK for the time being? Floor build-up is 150mm PIR, with 100mm dry screed with UFH loops embedded, then Marmoleum lino as the finish.

[Dave Jones]

some dodgy advice here.

 

you dont need a TRV with ASHP and UFH.

 

you dont need another pump for the UFH with a ASHP.

 

nothing stopping you adding both but not needed and reduces efficiency in the case of double pumps. 

[JohnMo]

41 minutes ago, ectoplasmosis said:

 

 

Thank you, very detailed and helpful.

 

We don't have much time nor money left over to change anything right now. Will our current setup, with the Reliance HEAT970366, be OK for the time being? Floor build-up is 150mm PIR, with 100mm dry screed with UFH loops embedded, then Marmoleum lino as the finish.

My steps would be

Set all thermostats and radiator valves to above room room temperature target. Set up your weather compensation without any interference from thermostats.

 

Longer term look to simplify everything to ASHP, diverter valve, possibly a mixer if you need it depending on where flow temperature lands for radiators and floor.

 

[ectoplasmosis]

On 15/07/2024 at 16:04, JohnMo said:

My steps would be

Set all thermostats and radiator valves to above room room temperature target. Set up your weather compensation without any interference from thermostats.

 

Longer term look to simplify everything to ASHP, diverter valve, possibly a mixer if you need it depending on where flow temperature lands for radiators and floor.

 

 

 

Thanks. If I set the Reliance thermostatic mixer valve to 55degC, which the flow temp will never reach, will this act as if the mixer doesn't exist? Or is the best approach in terms of efficiency to physically delete the mixer and secondary pump?

[JohnMo]

9 minutes ago, ectoplasmosis said:

which the flow temp will never reach, will this act as if the mixer doesn't exist?

From trying myself no. There is always mixing going on.

 

But having radiators and UFH your radiators will need a higher flow temp anyway (45) and floor maybe closer to 30. I would

 

Assuming you run the rads on weather compensation, get the curve set for that, set the UFH mixer at say 35 see what happens? Adjust from there. Concentrate on radiators first, then balance the flow temp on the UFH.

[ectoplasmosis]

Just now, JohnMo said:

From trying myself no. There is always mixing going on.

 

But having radiators and UFH your radiators will need a higher flow temp anyway (45) and floor maybe closer to 30. I would

 

Assuming you run the rads on weather compensation, get the curve set for that, set the UFH mixer at say 35 see what happens? Adjust from there. Concentrate on radiators first, then balance the flow temp on the UFH.

 

Thanks again. 

 

The entire system is new, and has been designed around a 45deg max flow temp at -3deg OAT. If I were to remove the blending valve and secondary pump, then run the whole lot as a single zone at the same flow temp, would this work well?

[JohnMo]

17 minutes ago, ectoplasmosis said:

would this work well?

I would try it first, UFH maybe too hot at 45. If it turns out it's not getting hot enough dump mixer and pump and it all fully open off the heat pump circulation pump.

 

Last thing you want is thermostats switching big sections of the heating system off, because the flow temp is way to high. Flow rate is king with heat pumps

[ectoplasmosis]

53 minutes ago, JohnMo said:

I would try it first, UFH maybe too hot at 45. If it turns out it's not getting hot enough dump mixer and pump and it all fully open off the heat pump circulation pump.

 

Last thing you want is thermostats switching big sections of the heating system off, because the flow temp is way to high. Flow rate is king with heat pumps

Everything is plumbed as a single open zone right now, single Vaillant controller running in pure weather comp mode, no buffer/volumiser/low loss header. Rads have been balanced. 
 

There is however a stat on the bathroom UFH loop set to close the loop if the temp in the bathroom reaches above 25degC, as there’s a large dual fuel towel rad in there as well, but the bathroom loop is tiny. 

[JohnMo]

10 minutes ago, ectoplasmosis said:

Everything is plumbed as a single open zone right now, single Vaillant controller running in pure weather comp mode, no buffer/volumiser/low loss header. Rads have been balanced. 
 

There is however a stat on the bathroom UFH loop set to close the loop if the temp in the bathroom reaches above 25degC, as there’s a large dual fuel towel rad in there as well, but the bathroom loop is tiny. 

Sounds good, so just a bit of fine tuning really on the UFH mixer.