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.

[Wil]

On 11/07/2020 at 19:38, Nickfromwales said:

Every UFH manifold needs a pump and a TMV. TMV’s  cannot be pumped through, they have to be ‘sucked’ on, ergo a pump needs to be downstream of a TMV in a heating setup. 
TMV caps the max temp the floor will ever see, I’m sure there’s a reg there but moot unless you intend to not fit one. You should not ( cannot ) rely on an external Ctrlr to guarantee that the slab / screws won’t see the max temp of the heat source, so if said Ctrlr failed, on an ASHP, you could get up to 55-60oC floor temp which will cook anything that’s not high-temp tolerant, plus it would be a health hazard ( if a toddler or elderly were to end up on it ) or if anyone walked onto it barefooted etc hence the reg. 

UFH manifolds need the local pump to circulate water through the loops, and the ASHP circulation pump send the water to / from the manifold. Think of it like a figure 8, with the two circuits being connected but hydraulically separate eg both pumps can circulate at different flow rates without conflicting with one another. 
The IVAR blending set also has an inbuilt bypass ( so the ASHP pump never sees a closed circuit ). 

 

First of all- HOLY THREAD RESSURECTION!

 

But hoping @Nickfromwales might be able to confirm if the advice above has been superseded-

The builder’s plumber turned up, saw an ASHP and looked no further. He then supplied a manifold with a pump and no mixing valve- just some sort of fixed 4 way and a pump.

 

I have the ability to run the oil boiler in to the heating circuit and the Buffer tank has an immersion in it- so I would consider a TMV still required. He just keeps saying ‘it’s fine for an ASHP’ - is it ever fine to not have a TMV?

[Nickfromwales]

1 minute ago, Wil said:

 

First of all- HOLY THREAD RESSURECTION!

 

But hoping @Nickfromwales might be able to confirm if the advice above has been superseded-

The builder’s plumber turned up, saw an ASHP and looked no further. He then supplied a manifold with a pump and no mixing valve- just some sort of fixed 4 way and a pump.

Lol.

 

1 minute ago, Wil said:

I have the ability to run the oil boiler in to the heating circuit and the Buffer tank has an immersion in it- so I would consider a TMV still required. He just keeps saying ‘it’s fine for an ASHP’ - is it ever fine to not have a TMV?

Not in this instance, so afaic you DEFO need a mixing valve here to cap the max flow temp into the floor.

[Wil]

@Nickfromwales Thank you.

 

If it was just an ASHP, would it be acceptable to have no control? Is there any point in the 4 port and pump? Why not just run it as a big radiator?

[Nickfromwales]

Just now, Wil said:

@Nickfromwales Thank you.

 

If it was just an ASHP, would it be acceptable to have no control? Is there any point in the 4 port and pump? Why not just run it as a big radiator?

Do you have a schematic you can share? 

[Wil]

A pretty terrible scribble, give me a few mins to tidy it up!

[Wil]

@Nickfromwales see scribbles below. Current above, planned below. The idea is I could eventually drop the oil and the 26kW ASHP but they’re there anyway so might as well use them.

 

 

[JohnMo]

19 minutes ago, Wil said:

26kW ASHP

What are you heating?  That 26kW isn't enough?

[Wil]

I’ve got an 18 and a 26 in a weird parallel situation (blame Cool Energy for the upsell!) I’m hoping to get to just the 18, but it does defrost a lot and the 26 helps carry through those moments.

[JohnMo]

Have you bought these heat pumps?

[Wil]

@JohnMoThey’ve been installed per top scribble for 3 years. I appreciate the ridiculous oversizing but I have another project this 26unit will move to once I finish the upgrades to the main house and can prove just the 18 copes.

 

this is the ASHP setup as per CE:

 

Edited Wednesday at 08:37 by Wil
Added diagram

[Nickfromwales]

44kw...!! Yikes.

 

Anyhoo, as you plan to reuse that elsewhere (which one will you remove btw?) pointless going over that.

 

On the proposed I saw the 2 HP's tee'd together to do DHW, but I assume that will no longer be the case; only 1x HP can do the DHW cycle obvs.

[Wil]

Yep, it certainly makes the meter spin when it all runs together.

 

Ah yes, only one can ever do the DHW, currently the 18. I would aim to drop the 26 altogether in the future. In the CE diagram 18 is on the left and 26 on the right. The intent of the proposed was to allow them to run in parallel for heating and one for DHW but that’s not what is shows!

 

I’ve read in the other threads about removing buffers and using volume of system (my house is plenty cold enough there’s valves open). But specifically at the moment is is the pumped UFH system the correct approach? Can I simplify as per JohnMo’s example or is the current setup optimal in terms of feed.

[Nickfromwales]

If there’s a single ASHP then you can do away with it as suggested, whilst the oil remains you should have a cap on the max permitted flow temp into the UFH. 
 

That means, as of now, you should have one. (afaic). 

[Wil]

@NickfromwalesThank you, I’ll insist he changes it.

[Nickfromwales]

3 hours ago, Wil said:

@NickfromwalesThank you, I’ll insist he changes it.

It won't need altering later, just may become an ornament that's the catch. Way too much Russian roulette here without it tbh.