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Wet Underfloor heating installation (renovation) (Read 925 times)
thescruff
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Re: Wet Underfloor heating installation (renovation)
Reply #25 - Aug 28th, 2018, 9:29am
 
Yes, born in Darley Dale November 15, same day as me  Cool
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big_all
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Re: Wet Underfloor heating installation (renovation)
Reply #24 - Aug 28th, 2018, 1:43am
 
hes a nipper lol
he come from derbyshire does he not  Grin
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thescruff
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Re: Wet Underfloor heating installation (renovation)
Reply #23 - Aug 26th, 2018, 10:27pm
 
Good Alan Thank You, refereeing Nigel Bond in an exhibition next month. In Yorkshire lol
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big_all
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Re: Wet Underfloor heating installation (renovation)
Reply #22 - Aug 25th, 2018, 10:03pm
 
good as gold scruffs  Grin
hows you ???
have you met ray reardon or len ganley yet  Grin
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thescruff
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Re: Wet Underfloor heating installation (renovation)
Reply #21 - Aug 25th, 2018, 8:27am
 
BA how are you by the way. Underfloor heating should be designed for a constant temperature with maybe a night set back of say 2-3 degs.

It should be run around 42c unlike radiators 70+c making it safer for kids-babies and at risk grown-ups, you don't program it to come for an hour when you feel chilly, which is why the need for a dedicated underfloor heating zone from the boiler.

I will agree, insulation is important so the more the better, but saying that modern houses are leak proof, at the end of the day a constant temperature of say 21c throughout the building is far better than hot blasts from radiators.

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Re: Wet Underfloor heating installation (renovation)
Reply #20 - Aug 24th, 2018, 11:51pm
 
thescruff wrote on Aug 21st, 2018, 5:08pm:
Big-all post misses the point of underfloor heating which should be designed to run at a constant low-temperature I.E. 42c give or take, any addition radiators or hot water should be zoned separately or combi plus 2 or more heating zones.



Any questions please ask


the point i am clumsily trying to make is
underfloor has a greater heat up time so needs to be fully specked and the thermal efficiency off the room is very crutial as is things like open doors and heating off other areas in the house as the heat up time can be hours unlike a radiator for the same situation that can be perhaps half an hour to 40 mins
in general a radiator will give out perhaps 3 or 4 times the heat off an underfloor matt
if the heat input is say 500w an hour and the heat loss is say 350 an hour your heat gain is 150w  an hour so quite slow heating up
where as a radiator for the same situation may be 900w which is less than twice the output but because the heat loss is 350w  the gain is 550w or nearing 4 times the heating rate off the underfloor at least at first when you most need it
and as the heat rises the heating rate improves for a radiator compared to underfloor
indeed if your heating is off for around half the day it may take 2 to 4 hours to get to the level you want dependant on situation
continuos in this situation means on day and night
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thescruff
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Re: Wet Underfloor heating installation (renovation)
Reply #19 - Aug 24th, 2018, 6:33pm
 
Lag the pipes, especially the mass of pipes in the floor that comes out of the manifold.

Keep all the loops at much the same length.
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Re: Wet Underfloor heating installation (renovation)
Reply #18 - Aug 24th, 2018, 4:34pm
 
I've never used it, was just an idea but I had originally planned on using PIR throughout so will continue to do so.

As for no heat I forgot the boiler is in there and so will the underfloor manifold so it will probably be the warmest place in the house Smiley
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Re: Wet Underfloor heating installation (renovation)
Reply #17 - Aug 24th, 2018, 7:46am
 
Personally, I hate Rockwool and would sooner pay a bit extra for Celotex or similar. I'm amazed it hasn't been banned by now.

Cold/unheated spaces leach heat from neighboring areas so need to be calculated for.
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Re: Wet Underfloor heating installation (renovation)
Reply #16 - Aug 23rd, 2018, 9:26pm
 
The gas pipes are out the way and go straight in under the stairs from outside They will be going through the insulation but that's it.

For areas such as under the stairs would you suggest using a cheaper insulation like rockwool as it can fill the full 130mm joist spacing and it's more to limit draughts than anything else as it will be a space that doesn't get used/occupied?
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Re: Wet Underfloor heating installation (renovation)
Reply #15 - Aug 23rd, 2018, 7:32pm
 
Ok, but no, gas pipe in the heated floor and if you have to go through the depth, sleeve it.
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Re: Wet Underfloor heating installation (renovation)
Reply #14 - Aug 23rd, 2018, 5:13pm
 
Thanks for all the help so far it has made me adjust my plans but it seems I can have a solid mass floor and able to do what I would like to with some alterations.

As for services I am planning to install a full new water pipework system as the one in there is lead piping for about half soldered to copper. I am putting in a new water supply anyway so I have mapped out the water piping system too.

This will run primarily up through the floor once 750mm in from the wall to come up through the floor behind the kitchen units. These run along the sides of two walls. From here I am going to duct it back under the floor through the insulation (where the units are there will be no screed only insulation so I am not heating under units and wasting heat, plus it means units and contents don't get warmed too).
The duct I will pack with something like mineral wool so it's not open and for draughts. The duct will run it on further to the boiler under the staircase. I will also use the same route back for the DHW to the sink.

I am looking into insulation I need if I am to run the cabling for the hob and ovens through the initial duct in the house (the hob and oven are close to where the water supply will come into the house through the wall so it makes sense to use the same duct. As this duct will only carry water supply from outside I am hoping there is very little needs doing for the cabling except for insulating it as a precaution (the water supply pipe will be very well insulated with 32mm Armaflex round it).

It has just had a full rewire which I wish I had waited on as things have had to be moved around the house. But the majority of what has been done needed to be done ASAP as some of the circuitry was from what looked to be the 1920's when the house was built
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thescruff
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Re: Wet Underfloor heating installation (renovation)
Reply #13 - Aug 22nd, 2018, 10:17am
 
A solid mass is always going to be better than the alternative systems.

If you can strengthen the joists (don't forget the DPC) between wall and wood. and you can get around the other services problems, I would say go for a 50mm screed minimum, remember the thicker the mass the longer it holds the heat.

One last hint, tack a DPC to the side of the joists to prevent any expansion noises.

I also suggest a vapour barrier before you lay the finish floor.
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Re: Wet Underfloor heating installation (renovation)
Reply #12 - Aug 21st, 2018, 9:50pm
 
As I am also taking out two chimneys and will have around 2000-2500 bricks going spare would it not be an option to support the joists in this way using a honeycomb (or less intensive) support structure to the joists that will enable them to in effect transfer the load to the ground?

I saw this today (link below) showing different warm ups. It shows 4 different set ups and the heat efficiency of all of them with the same parameters.
Obviously they're trying to sell their product but I doubt they can be so misleading as they've stated what they used for comparison. This is what I am obviously, unsuccessfully trying ti get in my home. The bottom left of the two, I.e. using a thinner screed (strengthened) but between the joists using as much of the joists spacing for insulation but leaving enough room for screed. I could go up over the joists a little as long as I then don't have to raise doors and frames.

https://www.youtube.com/watch?v=z75ikxSuTWk

If I am resigned to aluminium spreader plates I might just go back to using radiators as the whole point of the flooring was to have a constant lower heat which the aluminium plates go someway to doing but not like I'd hoped and nowhere near as efficient as I want.
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thescruff
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Re: Wet Underfloor heating installation (renovation)
Reply #11 - Aug 21st, 2018, 5:08pm
 
As promised.
130mm joists are not going to take the weight once you start hacking them about to run pipes through, you need the batten on the top to enable you to cross the joists to run the loops between them.

Running a 50mm + screed between the joists was quite common back in the day, however, it gives you a major headache with other services, both installing and access for maintenance.

Pipe size is critical to get the correct heat output, I suggest you contact the supplier who will give you a free floor plan showing the manifolds, pipe lengths, pipe sizes and the number of loops required. In other words, they will design it for you.

I would recommend you use the insulation and floor plates as per my pic, We used Roth products in the pic, one of the best in my opinion but please shop around for the best deals.
https://www.roth-uk.com/en/roth-downloads.php.

Lectrician, has post pics, look at them carefully, you must avoid air gaps as it stops the heat, some are unavoidable.

Big-all post misses the point of underfloor heating which should be designed to run at a constant low-temperature I.E. 42c give or take, any addition radiators or hot water should be zoned separately or combi plus 2 or more heating zones.

I agree with Woodsmith your initial plan would be a disaster, However, with the right screed (lightweight with insulation properties) and strengthen the joists it will work, you still have the other services problem, some of which cannot go in the same screed as underfloor heating.

Any questions please ask
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Re: Wet Underfloor heating installation (renovation)
Reply #10 - Aug 21st, 2018, 9:28am
 
Thanks for this. I did re-look at the screedboard and it appears it is laid on top of OSB which negates the need to have it in the first place. I was hoping to use it instead of ply for the thermal conductivity. Given it would have to go on top of the ply it makes no sense now.

Back to the drawing board it seems but much appreciated for telling me to go have another look, saves me wasting my time and what every little money I seem to have doing up a very old house Sad

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Re: Wet Underfloor heating installation (renovation)
Reply #9 - Aug 21st, 2018, 8:49am
 
This plan is just not going to work and will be a disaster if you try to implement it. I don't know where you have seen that you can fill the gap between joists with screed over insulation but I can only think you have misinterpreted their diagrams. Screedboard has absolutely no structural integrity at all and is designed to be fully bonded to a solid surface such as t&g plywood or chipboard, what you are planning is not going to work. If you want this confirmed contact the screedboard technical advice line on 01634296677

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