Plumbing in a Willis to UFH to dry screed - OK for beginners?

[Tom]

I really need to get some heat in to our screed and I'm thinking a Willis could do the job. Is this doable for a keen DIYer? Here is the manifold as it is now (it's the one on the left I need to get heat through).

Parts I'm guessing heater, expansion vessel, pump?, thermostat?

Thanks all

[jayc89]

That's a lot of loops. What's the total volume of water flowing through them?

[Tom]

Hmmm, eleven loops, guess average about 80m each, so 880m. What's the internal bore of Wunda pipe? Lets say 14mm, so that makes about 135 litres  - does that sound about right?

[Conor]

How long is your screed down? Don't want to dry it too fast! Good ventilation / or dehumidifiers work wonders. 

[Tom]

Thanks Conor, got the ventilation sorted as the build is nowhere near airtight yet. No point dehumidifiers as I'd be dehumidifying most of south Devon!

Screed been down for 10 days now.

[Conor]

You're still at the initial curing stages, you don't want to add heat for another two to three weeks minimum. Just keep windows open, don't rush it.

Edited October 2, 2023 by Conor

[Tom]

Ok, understood, but I guess any temporary heating system I try and install is going to involve several weeks of faffing.

[John Carroll]

22 hours ago, Tom said:

I really need to get some heat in to our screed and I'm thinking a Willis could do the job. Is this doable for a keen DIYer? Here is the manifold as it is now (it's the one on the left I need to get heat through).

Parts I'm guessing heater, expansion vessel, pump?, thermostat?

Thanks all

You left hand manifold has 11 loops, at a dT of 8C and a flowrate of say 2.5LPM will output 15.3kw so the willis at 3kw will do OK for initial heat up/drying out especially since you can set it's thermostat but hasn't a hope of supplying the required UFH output when drying out or whatever when completed.

[joth]

2 hours ago, John Carroll said:

hasn't a hope of supplying the required UFH output when drying out or whatever when completed.

Tbf that really depends more on the expected heating load (heat loss) of the property. Just cus it has a huge emitter kW capacity does not necessarily mean it actually needs to use that much 

(Obviously if you want to regularly reheat the property from cold, or blast heat in in a short window of time e.g. E7 cheap rate, it's a different matter, but a single cobbled together Willis heater doesn't sound like this is the goal anyways)

 

 

[John Carroll]

True, but generally the emitter would/should be matched however roughly to the expected heat loss, I think/hope the OP is only talking about the commissioning process, he is hardly going to oversize by a factor of ~ 5.

Edited October 3, 2023 by John Carroll

[Russell griffiths]

Leave the screed alone, adding any heat in my opinion is asking for trouble, get all the doors and windows open and let the breeze do its thing, trying to rush drying it is a recipe for problems later. 

 

If you needed it dry faster faster you should have used a faster drying product. 

It is what it is, get on with something else. 

[Andehh]

Next week is looking lovely and dry, warm & breezy... !

[Tom]

A few questions for those in the know if I can:

 

- would I need a circulation pump in addition to the one already on the manifold? I guess so, given that only circulates water round the loops

- could I run one 3kW willis off an extension lead and 13A plug?

 

Thanks all

[JohnMo]

38 minutes ago, Tom said:

would I need a circulation pump in addition to the one already on the manifold?

No, the one on the manifold will move the fluid around the loop

 

39 minutes ago, Tom said:

could I run one 3kW willis off an extension lead and 13A plug?

I wouldn't, not really suitable for 13A for a long period.

 

 

[oranjeboom]

If still looking, this is what I did (and still have)...

 

 

[Tom]

Cheers buddy. Last weekend I actually picked up a second hand electric boiler - which has pump etc already so will get that hooked up soon I hope.