UFH heating with Posi Joists

[richo106]

I have just had my quote from Wunda and now asked for a pipe layout etc

 

Do this lists below make sense and look like everything I need is included?

 

Where it says number of loops, what does that actually mean (sorry for the daft question)

 

The guy whos installing my heat pump says I will not need a mixer valve on the manifold as the heat pump controls the flow temp

 

Any body used the wunda wireless control set up before? Are they as easy to set up/install as described?

 

Any opinions/info on what I have provided will be very much appreciated 

 

[ProDave]

1 minute ago, richo106 said:

The guy whos installing my heat pump says I will not need a mixer valve on the manifold as the heat pump controls the flow temp

Yes and no.

 

If you have an ASHP and use it just for UFH he is probably right.

 

If you also heat DHW with the ASHP then no.  the ASHP will heat the water to probably 55 degrees for DHW, and when it has done, it will switch back to UFH and the slug of 55 degrees water in the system will promptly enter your UFH.

 

Fit the blending valve, as a precaution.

[SteamyTea]

3 minutes ago, richo106 said:

Where it says number of loops, what does that actually mean (sorry for the daft question)

It is what sets the power output for any given temperature.

[Nickfromwales]

13 minutes ago, richo106 said:

Where it says number of loops, what does that actually mean (sorry for the daft question)

It means each pair of pipes from / back to the manifold. So, one continuous piece of pipe has a flow connection to one manifold rail, and same for the return. Each pair of connections forms a "loop". 3 loops in your dining room for eg would require a 3 port manifold ( which would have 6 individual connections, 3 flow and 3 return ).   

[richo106]

I have just been told by my builder that he thinks the SE has specified joists at a mixture of 300 and 600mm centres. I was planning on using the spreader plates but they all seem to be at 400 centres.

 

Have i any other options to use spreader plates? 
 

plates that fix underneath the floor? Batten out the joists perpendicular using 25mm battens at 400 centres? And this could help with pipe routing with posi joists 

 

Would welcome any ideas 

 

thanks again 

[richo106]

15 hours ago, richo106 said:

I have just been told by my builder that he thinks the SE has specified joists at a mixture of 300 and 600mm centres. I was planning on using the spreader plates but they all seem to be at 400 centres.

 

Have i any other options to use spreader plates? 
 

plates that fix underneath the floor? Batten out the joists perpendicular using 25mm battens at 400 centres? And this could help with pipe routing with posi joists 

 

Would welcome any ideas 

 

thanks again 

I asked the SE and they said they can amend joists to 400 centers but obviously will affect joist sizes

Edited February 3, 2022 by richo106

[SteamyTea]

22 minutes ago, richo106 said:

I asked the SE and they said they can amend joists to 400 centers but obviously will affect joist sizes

Will that affect room heights?

[Scots Build]

I have UFH on my upper floor which is fed by an ASHP as well.  The diagram below shows the make up of it however if I was building again, I would, without a doubt, plan and budget for a concrete screed upstairs because the system of spreader plates, 22mm chipboard and then flooring (carpet and tiles) means the floor never gets warm and struggles to heat one of the bedrooms.  It has a fully glazed wall and the heat loss in that room through the glazing means the UFH cannot heat the room to a comfortable temp when the outside temp is very low (below 0). Air tightness of the house overall is 1m3/hr/m2 so air loss isn't the issue