Wet underfloor heating, change of floor levels and installation in different phases of the renovation

[Triumph]

hello.
I am considering installing a wet under floor heating system as part of a global renovation project over a long term.
My plan therefore as the project progresses I will be laying the UFH, as opposed to doing it all in one go (which is ideal I know).

1. Apart from not being ideal, is this feasabile? Any advise on how it should be done would be greatly appreciated. Note as each circuit is installed, it will not necessarily be commissioned and operational until the entire system in completed on that level of the house i.e ground floor level

2. In relation to the above, the ground floor, changes level throughout the area, such as; there is a step from kitchen and dinning room up to the living room, there are another 2 steps from from the living room up to the entrance hallway and another 3 steps up to the the utility room where the boiler is, how do you over come this problem of changing floor levels albeit I think (correct me if I am wrong), a different circuit and therefore zone will be installed for each area i.e Kitchen/dining 1 zone/circuit; living room another circuit/zone etc

Thank you in advance for any advise
Cordially
Bryan

 

[Cubist]

It's certainly feasible. A manifold, installed near the boiler, is used to control a water circuit for each room say thus allowing commissioning of the system on a room by room or floor by floor basis as you may require. Differing floor heights within a given room are usually dealt with by using simple plumbing adaptors but consideration needs to be given to any required modifications to the solid floor, steps, etc. to support the concealed installation of these and permit easy future access for repair.

 

[Triumph]

Dear Cubist,
Thank you for your very prompt and informative reply.
As the boiler is at the other opposite end of the house to the Kitchen/dinning > living room > entrance hall > Boiler /utility room
and my plan was to start the renovation at the kitchen/dinning > living room end first , so the circuit would stop (I.e the feed and return would not be installed all the way to the boiler, rather just the circuit piping within the actual room area) until the entrance hall way is done, would it be therefore terminate each circuit with its own manifold?
Thanks
Bryan

 

[Flyfisher]

Speaking from experience, I can confirm it's definitely feasible.
Our house had no heating apart from open fires and is quite large so the project has dragged on somewhat (er, just about finished now after about 15 years!) so I was more or less forced into a phased approach. The end result is two zones of wet UFH, two zones of radiators with a mains gas boiler and a multifuel boiler stove as the heat sources. Each of the UFH zones has its own manifold and the multiple zones means more circuits to control, which adds a bit to the cost, but on the other hand spreading it over many years also helped with the costs so I'd say that's about neutral. Not that I'm recommending a 15 year project!

One of the UFH zones was installed about two years before being connected into the system, as was some of the other pipework, so I'd say it's important to have a basic plan for the overall system so that the required pipework and cabling can be installed as any building/renovation works progress. For much the same reason, we have more electrical consumer units than might be expected. Better to install pipes and cables while building/renovation is in progress than have to retrofit them afterwards. Even if they don't end up being used, the cost (in both time and money) is minimal compared to retrofitting and then having to redecorate.

A potential downside to having so many zones is the additional pipework and control valves in the boiler room. Fortunately, we had a separate utility area to install everything as it's not the sort of installation that could easily be hidden away behind a kitchen cupboard. But the big advantage is that the system implementation can be rolled out one room or zone at a time. This was helpful in our project because our rooms also had floors at slightly different levels.

 

[Triumph]

Dear Flyfisher, thank your for the very encouraging reply.
Regards
Bryan

 

[Flyfisher]

You're most welcome. It sounds like you have an interesting project on your hands.

 

[Kearn]

All fine and feasible, as others have said, plan it all out before you start anything though, it will all have dependencies…and consequences!

Our kitchen is one zone, but 2 circuits off it’s own local manifold in the room, half up and running, the other floor hasn’t been dug out or the extension above it built yet, but provision is there - plastic soil pipe becomes your friend when laying floors as a conduit for later pipe work to run. Same goes for electrics as it happens.

Heights are no issue, as long as feeds can be run adequately. May be that these are not underground at all, none of our supply pipework is under the floor, only the pipes from the manifold.

I then decided to also install in the living room last minute, so have a separate manifold under the stairs adjacent to that room controlling it.
Our plumbers preferred the manifold as close to the circuit as possible, so our boiler room doesn’t have any more than the valves controlled by stats, and pipework to the appropriate manifolds. I’d very much suggest lining yourself up with a decent heating engineer/plumber who understands what they’re doing and can come up with ways to make things work. I can’t reiterate enough how much agreeing a plan, (then changing it endlessly!) upfront will save you in the long run, as with all old houses, nothing is ever isolated!

Good luck with it

 

[Triumph]

Dear Kearn.
Thank you for your reply.
Greatly appreciated, when you dug out, did you create a foundation "cone", i.e. leaving a 45 degree angle wedge of undisturbed earth, tapering in? If so what what the width of this wedge? 50cm?
My house is a stone rubble built house, thick walls, built directly onto the earth.
Thanks again
Bryan

 

[Kearn]

Yes indeed, don’t disturb the compacted earth around the footings. The width will be dictated by the depth, start a few inches at least from the wall, then go down at 45 until you reach your depth. common sense is your friend really.

Our current project is timber frame, sat on a stone plinth - footings are only 300mm wide and deep, but sat directly on bedrock.

 

[Triumph]

Thank you

 

[Cubist]

so the circuit would stop (I.e the feed and return would not be installed all the way to the boiler, rather just the circuit piping within the actual room area) until the entrance hall way is done, would it be therefore terminate each circuit with its own manifold?

Personally I would say that installing a separate manifold for that are would be a trifle wasteful and may introduce secondary challenges for you later. Provided you establish a clear plan for the final route of the pipe-work to and from the boiler and make all essential preparations beforehand it should not be a problem to install the UFH array and keep it dry until you're ready to make the final connections to the manifold beside the boiler. All this should be a simple plumbing task. However, you would be wise I think to test the integrity of the pipework laid in each section to ensure it is water-tight before you apply any final screeds or coatings to the floor - you definitely don't want to dig it all up again later when you make and turn on the boiler connection.

 

[Flyfisher]

However, you would be wise I think to test the integrity of the pipework laid in each section to ensure it is water-tight before you apply any final screeds or coatings to the floor - you definitely don't want to dig it all up again later when you make and turn on the boiler connection.

Agreed. The pipework I laid in a new limecrete floor was not connected to the heating system for a couple of years but we tested it by connected each circuit in series with a ball/lever valve at each end. The heating guy then added some compressed air and checked the pressure didn't drop, which it didn't. He checked it again after about a week when he collected his pressure gauge and it was still the same. We closed the valve before he disconnected his pressure gauge and left it like that for the two years or so before finally connecting it to the heating manifold, at which point there was a brief rush of air when we opened the lever valve!

 

[Triumph]

Thank you again Flyfisher

 

[Kearn]

Personally I would say that installing a separate manifold for that are would be a trifle wasteful and may introduce secondary challenges for you later. Provided you establish a clear plan for the final route of the pipe-work to and from the boiler and make all essential preparations beforehand it should not be a problem to install the UFH array and keep it dry until you're ready to make the final connections to the manifold beside the boiler. All this should be a simple plumbing task. However, you would be wise I think to test the integrity of the pipework laid in each section to ensure it is water-tight before you apply any final screeds or coatings to the floor - you definitely don't want to dig it all up again later when you make and turn on the boiler connection.

Indeed, we filled our circuits with water and popped a pressure gauge on. The first sat for quite a while before the limecrete went down. And then far longer before finally being commissioned…