beebee Posted September 2 Share Posted September 2 Hi all, have searched on the forum and I think I know the answer to this but just checking! We are partway through the foundations portion of a timber frame build by a passive house company in Ireland. Our plumber has informed us that the company he uses (danfoss/thermia) won't stand over any ufh installation in the concrete slab, they insist that it must be installed in a screed layer. Our options now are to 1. Add in 60mm of screed with all the associated drying time and floor height changes 2. Find a new plumber at short notice, or 3. Give up on ufh and go for a nilan air type system. The original floor buildup is 150mm 25n concrete with mesh/fibres over 2x100mm underfloor insulation. Any advice very welcome! Link to comment Share on other sites More sharing options...
JohnMo Posted September 2 Share Posted September 2 That is just nonsense. Sack him or tell you want what you asked for, there is zero warranty that means anything anyway. Sounds like he will be installing a high prices coil of tube. And possibly a load of additional bits you don't need especially in a passive house or anything close to one. You just need pert-al-pert pipes on 150 to 200mm centres, no more than 110m long per loop, to a suitable manifold. No zones, so no actuators or thermostats, no mixer no pump. Run the whole lot from heat pump or boiler on a very low weather comp curve. A wireless thermostat to control heat source. You really don't need him trotting off to do a design at your cost,once you get below 20W/m2 they come back rubbish anyway, massively over engineered. Link to comment Share on other sites More sharing options...
Alan Ambrose Posted September 2 Share Posted September 2 I think you need a new plumber. Some experienced people here on BH have installed / will install UFH in the slab. Means a bit of care, but you need a bit of care installing it in screed anyway. Link to comment Share on other sites More sharing options...
nod Posted September 2 Share Posted September 2 I’ve seen so many jobs where the pipes have been damaged in the slab Plus it’s all left open to the elements Unless there’s a massive saving by doing this Screed like most people 1 Link to comment Share on other sites More sharing options...
Gone West Posted September 2 Share Posted September 2 2 hours ago, beebee said: Give up on ufh and go for a nilan air type system. If your heating requirement is low enough I wouldn't bother installing UFH. In the last place we built there was a very low heating requirement and the whole house was kept at 23C with no problem. It was heated with three electric towel rails, one in each bathroom, and a Genvex Combi 185 with a built in MVHR, EASHP and DHW tank. Link to comment Share on other sites More sharing options...
beebee Posted September 2 Author Share Posted September 2 Plumber has installed this same heating system in the slab in dozens of houses in the area without issue and won't be charging us any different, he's apologetic about this new screed requirement but apparently the company has changed their "rules" in the past few weeks. Link to comment Share on other sites More sharing options...
JohnMo Posted September 2 Share Posted September 2 4 hours ago, beebee said: won't stand over any ufh installation in the concrete slab But what does this actually mean in reality. Assume they mean some form of warranty, but what does that cover? Link to comment Share on other sites More sharing options...
Nic Posted October 22 Share Posted October 22 Interesting post 🤔 My build is about to start next month . Having timber frame and passive principles. But not decided if I even need to go with UFH , which would clearly need to go onto the insulation and under the screed ? Or pop some electric mats or those new uv mats ( just in case ?) Link to comment Share on other sites More sharing options...
Smallholdertoo Posted October 29 Share Posted October 29 On 02/09/2024 at 13:44, nod said: I’ve seen so many jobs where the pipes have been damaged in the slab Plus it’s all left open to the elements Unless there’s a massive saving by doing this Screed like most people @nod What are the main causes of the damage? - contact with the Power float, scuff damage from boots etc. and how to best avoid if determined to have UFH pipes in the concrete slab ? Link to comment Share on other sites More sharing options...
JohnMo Posted October 29 Share Posted October 29 On 02/09/2024 at 13:44, nod said: I’ve seen so many jobs where the pipes have been damaged in the slab Plus it’s all left open to the elements Unless there’s a massive saving by doing this Screed like most people I finish the UFH pipe installation on the Sunday, filled with water and antifreeze and pressurised. Covered on the Tuesday with 100mm concrete. No damage etc. within a week or so we were getting zero temperatures no issues. On 22/10/2024 at 23:17, Nic said: But not decided if I even need to go with UFH Makes for a comfortable house. Some perspective, a heat loss of 2kW is 48kWh per day, via a heat pump that's 12kWh of energy, so £3. Can also cool Via gas about £2.5, can't do cooling via electric heat mats or any direct heating about £12. Can't cool Link to comment Share on other sites More sharing options...
Alan Ambrose Posted October 29 Share Posted October 29 >>> those new uv mats google says: greatly enhances play in the dark ooo, errr? Link to comment Share on other sites More sharing options...
nod Posted October 29 Share Posted October 29 2 hours ago, Smallholdertoo said: @nod What are the main causes of the damage? - contact with the Power float, scuff damage from boots etc. and how to best avoid if determined to have UFH pipes in the concrete slab ? Usually materials being dropped from height Steels blocks etc Or some numbty firing a fixing into the slab 1 Link to comment Share on other sites More sharing options...
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