Mike Posted May 26 Share Posted May 26 16 hours ago, JohnMo said: What point does heating the underside of my kitchen units serve The underside will heat up whether or not there are pipes, to the same temperature as the rest of the floor (though it will loose less heat when warm, of course). If there are pipes beneath it will heat up quicker, if you don't it will be slower. On the other hand, if you - or a future owner - change the layout, or change the use of the room (I've seen that happen) they would have a cooler patch where there are no pipes. Link to comment Share on other sites More sharing options...
Nickfromwales Posted May 27 Share Posted May 27 22 hours ago, Iceverge said: Added thermal storage? Yup. I’d rather the extra pipe / volume / storage tbh, particularly if it’s not a huge house. Not running pipes under things like kitchen islands etc is just a complete waste of time and effort in a passive type setting, as a) the temp is too low to cook your cornflakes lol, as you’re only ever getting the floor to a few degrees about room target temp so just entirely moot tbh, and b) as the heating is on ‘long and low’ the omitted areas will warm up anyways! It’s in an insulted basket, so the heat will eventually get there folks, and there’s nowt you can do to stop it. I will leave a pipe at the start of the run of fixed kitchen / other units, stopping about 150mm into the dead under-plinth space, leaving an unheated perimeter of around 450mm in the slab, and then it’s ‘fill yer boots, matey’. I’ve been installing / or been in and around / specifying M&E for these types of (PH style) systems for over a decade now, first ‘taste’ was an MBC PH TF, and not looked backed since. These Pert pipes are 1000% kosher to attach near to / directly to steel reinforcement mesh and the results are always excellent. Damage to the pipe must literally be malicious to get it to the point where it’s a total loss. “People of Buildhub, go forth and zip-tie”. 🫡. El Presidenté. 3 Link to comment Share on other sites More sharing options...
JohnMo Posted May 27 Share Posted May 27 2 hours ago, Nickfromwales said: El Presidenté Are you trying to get elected or something. 1 Link to comment Share on other sites More sharing options...
LnP Posted May 27 Share Posted May 27 2 hours ago, Nickfromwales said: Not running pipes under things like kitchen islands etc is just a complete waste of time and effort in a passive type setting ... I will leave a pipe at the start of the run of fixed kitchen / other units, stopping about 150mm into the dead under-plinth space, leaving an unheated perimeter of around 450mm in the slab... I'm a bit confused here. Seems like on the one hand you're recommending to run pipes over the whole floor area .... but on the other hand not....? Please clarify what you're recommending be done under fixed kitchen units! I don't understand! Thanks 😊 Link to comment Share on other sites More sharing options...
TerryE Posted May 27 Share Posted May 27 About a month or so back I did a post about reconciling my as-measured slab performance to a theoretical treatment. In short you consider my MBC slab in terms of either the 100mm slab area where the UFH loops run (say 10 tonne), or the total slab volume -- that is: including the load bearing 300mm ring and cross beams, plus the 200mm cross-bracers (say 17 tonnes). In terms of overall heat retention and release the best fit approximation was about 90% of the higher figure: the whole slab effectively acted as a heat battery and not just the areas with UFH looping. Even though the specific conductivity of concrete is relatively low, there is a lot of rebar in the slab and it is an extremely good conductor (see this post for numbers) and over the hour to few hours timescale, the heat is spread throughout the slab, and v.v. is the UFH is off and the heat is being slowly radiated into the living space. 1 Link to comment Share on other sites More sharing options...
Nick Laslett Posted May 27 Share Posted May 27 On 26/05/2024 at 08:15, TerryE said: How? What measure of efficiency? You've lost me here. @Nick Laslett MBC have been doing this with their slabs for a decade. I have an MBC slab. Their team did mine at the weekends, whist doing MBC ones in the week. Link to comment Share on other sites More sharing options...
Duncan62 Posted May 27 Author Share Posted May 27 10 hours ago, Nickfromwales said: These Pert pipes are 1000% kosher to attach near to / directly to steel reinforcement mesh and the results are always excellent. Damage to the pipe must literally be malicious to get it to the point where it’s a total loss. So standing on it during/after installation is ok...? Does attaching the manifold and pressurising it help against crush damage potentially? I'm just worried about contractors stepping all over it during concrete slab pour...? Link to comment Share on other sites More sharing options...
Nickfromwales Posted May 27 Share Posted May 27 11 hours ago, LnP said: I'm a bit confused here. Seems like on the one hand you're recommending to run pipes over the whole floor area .... but on the other hand not....? Please clarify what you're recommending be done under fixed kitchen units! I don't understand! Thanks 😊 Apologies. Things like kitchen islands or peninsulas are typically 600mm / 900mm / 1200mm deep or wide, so not installing UFH under these is pointless as the heat will get into the 'unheated' area anyway. Where there is a kitchen, and it can only have units on one or more wall, then I do not populate all the dead under cabinet space there as it will never be an emitter, per-se, but also there is always an unheated perimeter around a room with any good UFH design so I simply exaggerate that where kitchen units are always going to be located for the life of the dwelling. Islands and peninsulas come and go with design changes during re-modelling, so I just keep all such areas populated with pipe there. 1 Link to comment Share on other sites More sharing options...
Nickfromwales Posted May 27 Share Posted May 27 3 hours ago, Duncan62 said: So standing on it during/after installation is ok...? Does attaching the manifold and pressurising it help against crush damage potentially? I'm just worried about contractors stepping all over it during concrete slab pour...? You can pressure test to sleep better, but I've not bothered more times than I've bothered, it's just that amount of confidence that I have in it. 25 years of installing UFH and no issues to date btw. This is a rock solid pipe, so does not 'inflate' like a balloon.....so pressurising with a bit of air or water will do zero to protect it from getting crushed. My screed guy has up-ended a barrow full of screed on a pipe and it only scuffed it. I wasn't happy his labourer did it, but I was impressed how much of a hiding this pipe actually takes. I'm not advocating a blasé approach or attitude, and prevention is better than cure, but by simply coordinating trades so you're getting the pipe down, and getting the concrete down asap afterwards, this will massively minimise risks / damage. Not employing morons will pay dividends here, obviously..... Link to comment Share on other sites More sharing options...
mvincentd Posted June 4 Share Posted June 4 Scroll to july 21 and 22 entries when floor is being poured. It worked, the pipes are ok, the system works well.........but make a point of being 'away' the day they pour yours if you go this route as the stress of watching them trample all over it is awful....they cannot with the best will in the world tread carefully while laying the slab. Despite success I would not reccomend this route unless like me circumstances forced it. Link to comment Share on other sites More sharing options...
mvincentd Posted June 4 Share Posted June 4 http://2gomadindorset.blogspot.com/ Link to comment Share on other sites More sharing options...
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