Nickfromwales

Yup. +1 50 in liquid will be ok, not great, but it’ll last and do what it’s supposed to. Floor will be just like a slow radiator at that thickness so no real issue. Will allow the heating to be ‘timed’ as it’ll respond quickly. A benefit in some folks eyes.

What score were you looking to achieve? Are you referring to trickle vents in the doors and windows?

Lol. I don't actually want you to have a fight ( honest )...... Well, maybe just a little one, and upload to YouTube?

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IIRC it's already fitted with a pump and TMV. I'm away until tomorrow PM, then I'll dig it out.

FIGHT!!!

How many ports do you need for the manifold? I'll dig that one I got out and post some pics of it. If it works for you it's yours for a pint.

Work out how much surplus you need to routinely dump and do the maths there. Pointless trying to dump a load of excess into a tiny ( 25L ) buffer. In honesty it’s rubbish as in the winter you’ll be lucky to see 25% PV output which will prob be enough to still be pulling from the grid most days ( so no surplus ). PV > heating = ?

Agree that 25mm will only be of benefit to affix the pipes with pipe staples. I’d bin the 25mm insulation and just use clip rails direct onto the slab, fixed down with a Spit nailer. Then sand and cement ( dry ) screed at 50mm thick.

Not put Willis heaters in upside down that’s for sure If I didn’t get bad luck, I wouldn’t have any. Yay.

Hence my comment on you asking where you can add another external heat source. It was general advice, sorry. Just texting between disasters atm so take with a pinch of salt ?

‘Twas a ticking time bomb my friend. This was just a crash that hadn’t yet happened, now it’s happened. “Simples” ( insert picture of smug looking rodent here ). The above arrangement does not lend itself to having any additional external heat source of any kind. This is a temporary rig only.

Electric combi boilers are crap. Stick with gas. Don't forget the costs of an enormous supply cable and possible fuse board ( CU ) upgrade to cope with the high current demand of the combi. If you have an electric solution for cooking, you'll also need to see if you have enough current coming into the house to cope. Bad idea.

These things are brazed shut, sealed units. The only access for viewing is through the pipe entries. These are just kettling as the water flow rate through them is way too low / slow when the TMV nears the target / set flow temp. Needs a second pump as per my Rolf Harris drawing, and then you'll be fine.

Please tell me you have 2 x 20a switches not one 20a switch and the feeds to both heaters doubled up off the one supply?

You cannot do that. You'll have to alter it to have a pump and a recirculating loop. The heaters are kettling and overheating.

Are you running the Willis heaters through a constantly recirculating loop with its own pump? Then the UFH should be Teed into that loop for flow and return to the manifold pump? A bit like a figure of 8 with the two pumps remaining hydraulically separate from each other. If so, the pump speed of the Willis circuit is too low. Have you turned the 2 Willis heaters down on the internal stats? They should be set to no more than 45oC.

The second DPM, is it a slip membrane that we're actually talking about here? That would be employed if you are having a liquid screed vs a dry sand & cement based screed. If you are having a dry screed, some screeders will have a flap about the screed reacting with the foil layer of the PIR. You can mitigate against this by not having a foil backed product. Details please?

Diamond are great value for money, but Impey are the better trays. Impey systems require use of their own tanking membrane ( it tanks AND decouples ) so expect to part with more cash if you choose those. Wedi do a 40mm system but it needs a lot of supporting from underneath. I can’t recall them doing a 22/25mm system but haven’t looked at Wedi for some time now.

You need to find out IF there are issues as pointless discussing if the work is sound. Once you identify anything, and know the severity ( immediately unsafe work for eg which is about as bad as it could get ) then you can look at their governing body acting upon that information and possibly striking them off. If you paid cash, and don’t have an invoice, all that goes out of the window. If you have an invoice you need to contact that person and give them one last opportunity to rectify and provide the certification with immediate effect.

The low volume in the LLH isn’t that relevant. Flow to the manifold pump will be there in abundance as the flow will just ignore ( shoot straight through ) the LLH when it wants ‘full wallop’ and then flow will just simply recirculate ‘through / around’ it when needing nowt / next-to-nowt. The CH flow and return will prob be best off running through the LLH instead of being T’d off the single pipe tbh so the premium heated water has to flow through to continue its onward journey. All we need here is hydraulic separation. Thinking SP flow into top of LLH, then onwards flow ( aka return ) from lower connection ( same side ), and then flow to manifold pump from top connection other side, manifold return below that.

All lies

Just crack the valve shut at then open it to be set at 40% open. Test the system and move in 5% increments until happy. Simples. Flow dynamics are completely academic as the system will always see different flow rates to the various heating at various times. Put the calculator down, and go for Neanderthal maths Open it 100%, and count the turns to shut it. From that you can work out how to ascertain open %.

Pop some floorboards maybe and hope for the best?