UFH expansion sleeves

[MortarThePoint]

I'm going for Cemfloor Therm and the installer said he puts pieces of plywood in the doorways to encourage localised crack. I had already started installing 'pipe expansion sleeves' aka 25mm flexible conduit in the doorways and he said not to bother. Magnus Magnuson, I did it in all doorways. You can see an example below, a bit difficult as it's white. I put them on the pipe as laid, so unless I forgot and added later, they don't have skits along their length making removal difficult.

 

Is this a mistake, should I remove them all? Screed is going in at 50mm nominal and needs 25mm over pipes which it would achieve over these unless the float up slightly.

 

[MortarThePoint]

In this installation video from Cemfloor about expansion joints, they haven't added any sleeves at the joints, but I do notice that what I presume is the Flow pipe has conduit around it for a long distance. Insulation I guess.

 

https://cemfloor.co.uk/training/

STEP 3

Edited August 6, 2021 by MortarThePoint

[MortarThePoint]

@Nickfromwales and @Russell griffiths Sorry to tap you up on this but you've normally got a good view on all this. I'm about to attach my eurocones so removing these after that would be tricky.

[Nickfromwales]

Ok, firstly if it’s a liquid screed, both ends of any sleeve would need to be sealed to stop them simply filling up entirely. Your pics show open ended sleeves, both ends, so these will fill with screed and do the square root of FA.

If you have rooms very far from the manifold, it helps to insulate the flow pipe so as to preserve the premium temp water so it arrives at the zone it serves at as close to the TMV ‘injection temperature’ as possible. I see a lot of poor performing installs where the furthest zones really drag behind the others, some don’t get up to temp at all as all the heat has ‘gone’ by the time it arrives at its target area. 
I always shutter around the UFH pipes where they congregate at the manifold location, which allows for the pipes to be dressed in and bent / straightened to line up with the manifold nicely. Where necessary I also insulate the first 1-2m or more of each flow pipes that is serving a zone that is not local to the manifold. House / installation size / slab vs screed etc are all factors I consider when determining whether this is required tbh. 9mm wall insulation is sufficient, but again needs to be sealed and ‘waterproof’ so the liquid screed doesn’t get inside.

As far as just using a sleeve, it is a good idea in terms of protecting the pipe where it may be damaged where it’s above floor level, but your proposals for expansion via use of bits of sleeve ‘here and there’ is of zero practical use afaic. 
Take the advice of the guys laying the screed, as this advice differs with different types / thickness / etc and each job needs to be advised on its own merits.

[Russell griffiths]

As above, fat bloke knows what he’s talking about. 

[MortarThePoint]

Thanks Nick. It's always difficult to know what's important good practice and what's good practice according to people who sit in an office and write documents. There are various sources that say to use expansion sleeves (e.g. LABC, Underfloor Heating Trade Supplies) but on site practice is a more useful guide in many cases.

 

The main downsides of having them are the installation faff and the increased depth of screed to cover a thicker item. I sent the image to the installer and he said fine as long as has the minimum cover. I've decided I'll leave them in as they are where the screed needs to be thicker due to hollowcore camber anyway. There is one place where this isn't true, and I'll remove them from there.

 

21 minutes ago, Nickfromwales said:

Your pics show open ended sleeves, both ends, so these will fill with screed and do the square root of FA.

I was assuming the screed would be too porridge like to flow in. Pure water would, but will the screed really flow into a 300mm long 3mm wide channel?

 

26 minutes ago, Nickfromwales said:

If you have rooms very far from the manifold, it helps to insulate the flow pipe so as to preserve the premium temp water so it arrives at the zone it serves at as close to the TMV ‘injection temperature’ as possible.

I've no zones which are particularly far from the manifold. The furthest is probably about 4m upstairs so hopefully that will be fine.

 

[Nickfromwales]

3 hours ago, MortarThePoint said:

I was assuming the screed would be too porridge like to flow in. Pure water would, but will the screed really flow into a 300mm long 3mm wide channel?

Nope. It’ll get in those just fine. ?

3 hours ago, MortarThePoint said:

about 4m upstairs

Do you have a loop above the manifold? 

[MortarThePoint]

14 minutes ago, Nickfromwales said:

Nope. It’ll get in those just fine. ?

Do you have a loop above the manifold? 

 

Do you mean on a different floor (GF Vs FF)? If so, no each manifold serves one floor only

Edited August 7, 2021 by MortarThePoint

[MortarThePoint]

Just started my pressure test. Fingers crossed!

 

I'm off to drill some holes near the UFH pipes now

[MortarThePoint]

Two holes drilled, one exciting moment

Pressure holding so far

Beer chilling ?

[markc]

3 minutes ago, MortarThePoint said:

Two holes drilled, one exciting moment

Pressure holding so far

Beer chilling ?

You playing Russian roulette?

[MortarThePoint]

14 minutes ago, markc said:

You playing Russian roulette?

Feels like it sometimes ?

 

Pressure still holding after 1 hour. Cold beer opened. It's been a long week (>80 hours)

 

PS: don't ask why that loop looks so drunk. I had to cram in an extra pass at the edge of the room.

[Russell griffiths]

Remember to drop the pressure when the screed is in, the heat from the curing process increases the pressure. 

Mine hit 12 bar before I spotted it. ??‍♂️?

[MortarThePoint]

This is a concern. Pressure vs time

0         5.2bar

1hour 5.4bar

2hours 5.2bar

3hours 5.0bar

14hours 3.3bar

That feels like too much pressure drop for it to be 'stabilisation'. I've run my fingers over all the manifold connections and they are dry.

 

I guess my next step is repressurise and to start closing loops. Does anyone know if the flow and actuator valves are pressure tight? If not that approach won't work.

 

I haven't used any PTFE tape anywhere.

 

[dpmiller]

did the temperature drop overnight?

[MortarThePoint]

A little bit I guess. I didn't read it, I should check. Maybe 5C lower temperature.

[dpmiller]

that would likely do it. See if it comes back up a bit today...

[Russell griffiths]

If you have a leak that needle will drop like a stone, it will literally flop straight around to zero. 

To give yourself a reality check, crack a valve open the tiniest bit, you will see an instant drop. 

[MortarThePoint]

1 hour ago, Russell griffiths said:

If you have a leak that needle will drop like a stone, it will literally flop straight around to zero. 

To give yourself a reality check, crack a valve open the tiniest bit, you will see an instant drop. 

Thanks. It's holding steady at around 3.3bar so I'm going to give it a few hours before I do anything.

[Nickfromwales]

It’s 100% sound. Chill out. The pressure fluctuations are just relative to changes in ambient temp. 
Go drink more beer. ?

[MortarThePoint]

2 hours ago, Nickfromwales said:

It’s 100% sound. Chill out. The pressure fluctuations are just relative to changes in ambient temp. 
Go drink more beer. ?

 

Looks promising as the pressure has ticked up a bit to 4.0bar. Another beer chilling in the fridge.

 

[MortarThePoint]

The screed is in and looks awesome to me. The pressure rose and I let a bit out (into the capped off end of an isolation valve). My gauge only goes up to 6bar and It maxed out during the pour having started at around 4bar. I'd guess it got up to 7 or 8 bar, but that's a guess. Back down now. I'm really impressed with how flat and level it is. I've put my 2m level down in a number of places and can't see any real gap under it. There are a very small number of bumps that are kind of like a piece of aggregate causing a 1-2mm hump about 5mm wide. I'm sure those are super easily sorted and I'm pleased.

 

Thanks for the help getting ready for it ?

Edited August 12, 2021 by MortarThePoint

[RHayes]

Sounds good MortarThePoint

 

What type of screed has been used?  Is is a dry sand and cement type or more of a flowing/liquid screed?  If its a flowing screed then in most cases the latence will need to be removed any time from about a week/10 days after and some screeders offer this as part of the job.  This will take out any of these small bumps you have.

[MortarThePoint]

25 minutes ago, RHayes said:

Sounds good MortarThePoint

 

What type of screed has been used?  Is is a dry sand and cement type or more of a flowing/liquid screed?  If its a flowing screed then in most cases the latence will need to be removed any time from about a week/10 days after and some screeders offer this as part of the job.  This will take out any of these small bumps you have.

 

It's Cemfloor Therm which is cement based liquid screed able to walk on after 24-48 hours. I had considered Thermio+ which is an Anhydrite screed, but I wasn't keen on it's durability against water and the latiance which I was quoted £720 to remove. I could have gone thinner with Thermio+ (above UFH pipes: 20mm vs 25mm), but I don't consider that an issue. Similar, but Cemfloor Therm has a better thermal conductivity (2.9 vs 2.5).