This guide is aimed at providing you with information on repairing a wet (water based) underfloor heating system. Due to the many variations in both system design and available components this can only be a superficial look at underfloor heating repair.
This guide is aimed at plumbers and heating engineers that are competent but lack experience with underfloor heating systems.
Please ensure that you have the necessary skills and experience, and take all necessary safety precautions, before starting work as Thermotech cannot be responsible for damage or personal injury caused by an inexperienced person attempting to follow this advice.
Faults with wet underfloor heating systems can be split into three basic categories.
No heat from system
Heating is not controllable
This article will deal with system leaks, other topics will be dealt with in individual articles on underfloor heating repair.
Leaks can either be exposed or concealed.
Exposed leaks are from components other than pipe loops.
These include; pumps, manifolds, manifold heads, change-over valves and isolation valves. Generally these components are in the same area and it should be a simple matter to locate the source of the leak.
Be aware that some underfloor heating systems will have a main manifold with a distributor, or secondary, manifold in each room.
The greatest difficulty that often arises is that many underfloor heating systems use imported components that are not to UK specification.
Unless you are already well equipped with a range of non-standard fittings then you are most likely faced with the situation of obtaining the part and revisiting the property to effect a repair. You may be able to effect a short-term repair with the usual putties and tapes etc.
Concealed leaks should only be as a result of damage to the pipe loop, as there should not normally be pipe joins in the floor. Having said that, we have encountered systems where the pipe has been joined from installation, or where a previous pipe repair has failed.
The first thing to do is establish that there is a leak on concealed pipework.
Turn off the heating pump and all the heating loops at the manifold.
Pressurise the system and establish a stable pressure.
Open each loop in turn, allowing at least 10 minutes before opening another, until the pressure drops.
When a drop is noticed make a note of the loop involved and close it off again.
Continue with this process until all loops have been checked, just in case more than one loop is losing pressure.
Return to the loop(s) that was previously identified and ascertain from the system documents (if any) which room(s) this covers.
In the absence of thermal imaging cameras you would need to lift up the floor coverings in the room(s) concerned, along with the run back from that room to the manifold.
Once the location of the leak is identified the floor at that point will need to be lifted or excavated, depending on the structure (timber or concrete and screed) to effect a repair using a connector.
The type of connector will depend on the pipe system used, some will use a standard compression type fitting while others will require specific compression tools.