Ramping up UF heating

[JackofAll]

Hi,

Starting @ 20deg temp (lowest setting)what's the max I need to hit to see if any cracks appear before shutting off to allow cool and tiling prep can start? Bear in mind it's 6 inches of concrete.

[nod]

It’s more after the tiling that you need to heat up slowly Most of the floors I tile haven’t had the UFH commissioned

Make sure the floor has dried out 

[JackofAll]

9 minutes ago, nod said:

It’s more after the tiling that you need to heat up slowly Most of the floors I tile haven’t had the UFH commissioned

Make sure the floor has dried out 

Thanks Nod, few tilers looked at it and said that i would need to get the heating up and running (which it now is) 1 deg a day for a few weeks and allow to cool for a week before tiling could commence, it's now set at 30 degrees and tbh will never be set that high again(21, maybe 22 if she gets her way). Floor is down since July 23. so it will be no harm to do the same thing again once the tiles are down, thanks again.

[JohnMo]

I just didn't bother. For the first year we never went above 30 Deg flow temp anyway, operating on WC. Now we batch charge the temps are a little higher, but not much.

 

The whole cycling thing is really for properties that require 45 plus degs all the time.

[nod]

1 hour ago, JackofAll said:

Thanks Nod, few tilers looked at it and said that i would need to get the heating up and running (which it now is) 1 deg a day for a few weeks and allow to cool for a week before tiling could commence, it's now set at 30 degrees and tbh will never be set that high again(21, maybe 22 if she gets her way). Floor is down since July 23. so it will be no harm to do the same thing again once the tiles are down, thanks again.

I’ve run both my builds heating before tiling But in reality most commercial builds are miles off heating being up and running 

A multi million pound house that I’m ting at the moment 750M2 of tiling plus the swimming pool 

Is six months off commissioning the heat pumps 

and he’s opted for traditional screed 

 

[Nickfromwales]

3 hours ago, JackofAll said:

few tilers looked at it and said that i would need to get the heating up and running (which it now is) 1 deg a day for a few weeks and allow to cool for a week before tiling could commence

They refer to this as "thermal shocking", but tbh I think I've done this twice in 20 years and doubt it made any difference. Reason being is that the slabs / screeds have never been down and then laid on. Any that have I have just used a decoupling membrane to cheat the risk of cracks migrating through to the finished floor.

 

At 6" of concrete (and assuming some mesh in there, if not 2 layers of?) and the fact it's been down for nearly 2 years means this has done anything it's ever going to do already, and I'd not even bother with expansion gaps at the doorways.

 

As you say, the flow temp will be very low 20's so this will all expand and contract (if ever) at the same rate of knots at the beginning and end of each heating season and life will go on.

 

Your tradespeople are 100% correct to follow the path of due diligence as you'd be the first to complain and sue if the 'cracks began to appear' so they're rightfully covering their arses as would I. Follow their advice and then you have full recourse.

 

Just ask that they use a quality flexible adhesive, and that the slab is thoroughly cleaned / prepped / primed so the adhesive has excellent purchase on the concrete, after that I doubt you have anything to worry about here at all; sounds like you have tilers who GAF too which is reassuring.

[saveasteading]

@JackofAll

A heart isn't enough. So to emphasise @Nickfromwaleshas it dead right on all counts.

 

In reality concrete doesn't shrink much after the first month or so and that is a chemical reaction, not evaporation.

[SteamyTea]

32 minutes ago, saveasteading said:

and that is a chemical reaction, not evaporation.

No matter how often we say that, it does not sink in.

Cure and Set are my preferred terms for the hardening.

[saveasteading]

12 minutes ago, SteamyTea said:

it does not sink in

Because most builders have no training, and not the slightest interest in it.

 

I've even had concrete gangers who clearly think I'm deluded, and they will nod then ignore. 

Of course concrete dries, what harm is more water. 

 

I guess everyone knows (not understands) that drying happens with heat or wind.

Not many will have understanding that chemical reactions happen.

 

They suddenly take it seriously when told that if they add any water to the mix, they won't be paid.

Edited April 25 by saveasteading

[SteamyTea]

46 minutes ago, saveasteading said:

Of course concrete dries, what harm is more water. 

Try explaining to them how water based paints set and then can't been softened with water.

[JohnMo]

4 minutes ago, SteamyTea said:

Try explaining to them how water based paints set and then can't been softened with water.

Or that PU glue (Gorilla) needs water to activate the expanding and curing process, and then it's water proof.

[SteamyTea]

24 minutes ago, JohnMo said:

Or that PU glue (Gorilla) needs water to activate the expanding and curing process

Almost.

PUs do not need water to cure, but water is a 'blowing' agent that makes it expand.  It is the isocyanate that makes the polyols harden.

CFCs are another blowing agent, but they have been phased out, fluorine is wicked element, wants to react with just about everything, so was not good for the workers making furniture and car seats.

Isocyanate and CFC make for an interesting combination in chemistry.

[Nickfromwales]

1 minute ago, SteamyTea said:

Almost.

PUs do not need water to cure, but water is a 'blowing' agent that makes it expand.  It is the isocyanate that makes the polyols harden.

CFCs are another blowing agent, but they have been phased out, fluorine is wicked element, wants to react with just about everything, so was not good for the workers making furniture and car seats.

Isocyanate and CFC make for an interesting combination in chemistry.

Why does the packaging say "moisture cure"? Pretty sure that's how 'they' word it.

[Nickfromwales]

Our best waterproof adhesive is PU30.  In a nutshell, it is a ‘half-hour’ solvent-free moisture curing PU wood glue. It is rapid-setting and the initial bond strength is achieved within 30 minutes.
Because it has an open time of up to 20 mins (10 mins if glue-line is misted with water), it is easy to work with. Also, due to its chemical composition, it is ideal for bonding wood-based materials where a water-proof bond is required.

[SteamyTea]

1 minute ago, Nickfromwales said:

Why does the packaging say "moisture cure"? Pretty sure that's how 'they' word it.

Marketing puff, written by people that do not understand, and care even less, for science.

I suspect that what they mean is it will cure on damp surfaces.

 

Superglue is different, that needs the hydroxide ions in water to polymerise the C=C groups.

[Nickfromwales]

Odd, as in practice the difference when introducing water to the foam during application is night and day, and yields massive benefits / results.

[nod]

3 hours ago, saveasteading said:

Because most builders have no training, and not the slightest interest in it.

 

I've even had concrete gangers who clearly think I'm deluded, and they will nod then ignore. 

Of course concrete dries, what harm is more water. 

 

I guess everyone knows (not understands) that drying happens with heat or wind.

Not many will have understanding that chemical reactions happen.

 

They suddenly take it seriously when told that if they add any water to the mix, they won't be paid.

More likely walk off site if you start telling them how to do there job