Go With The Flow - Extending An Existing Underfloor Heating System
As many householders take the decision to improve instead of move the issue of extending their UFH arises and the installer must be aware what needs to be considered.
As with any extension to a heating system the first thing to discover is whether the current heat source is large enough and how to route any flow and return pipe work. Additionally, with UFH consideration must be given to positioning of the manifolds and the route from there to the UFH zones.
There are two basic methods of adding capacity to the system:
- Using existing manifolds
- Adding new manifolds
Using existing manifolds
Using an existing manifold may remove the necessity of installing new flow and return pipe work. However, this may not be the case as the larger the manifold the bigger the feed pipe to it needs to be. Continental's advice is that 22mm diameter pipe should be used for manifolds up to eight zones and 28mm pipe for manifolds over eight zones. Routing the UFH pipe to the new area may not be possible, or result in long feeds by comparison to the heating loops. Also, to ensure air is removed from the system the manifold must be located above the heating pipe work. A downstairs manifold should not be used for upstairs UFH.
Space can also be an issue when using an existing manifold. The smallest expansion section is two zones. Blanking plugs are available to shut off any unwanted manifold zones.
To add the manifold extension manifold couplers are required and can be put at either end of the manifold, although adding them at the mixer/pump end of the manifold will require modifications to the flow and return pipe work. Adding the new zones at the end set end of the manifold is more usual. To do this the manifold must be sealed off using the isolation valves at the pump end of the manifold. Pressure can then be reduced in the manifold, prior to dropping the water out of the manifold through the end set on the lower manifold rail. The water in the current UFH zones will not leak out as the manifold is above the UFH pipe.
The end sets can then be removed and the couplers and new section of manifold added, with the end sets being reinstalled on the new end of the manifold. It is possible to use 90° couplers to either turn the manifold section through 90° or by using two set of couplers to bring it back on itself. Once the new zones have been connected onto the manifold the end sets can be used to fill the new zones with water. The system should then be pressure tested to confirm there are no leaks.
Continental controls are modular and so adding more control zones should not present a problem. However, if it is not possible to route from the thermostats in the new area back to the manifold then Continental's standard Heatmax™ thermostats all come in a radio frequency version.
Adding a new manifold
If it is not possible to use an existing manifold then a new one can be installed. Adding a new manifold to the system requires similar requirements to when the original system was installed. The manifold position has to be chosen for ease of installing the heating zones and the straightforwardness in getting the required flow and return pipe work from the heat source to the new manifold. As with extending a manifold, once the system has been installed the UFH zones need to be filled via the end sets and pressure tested.
The wiring of thermostats back to the manifold can also be simplified by the use of radio frequency units. The new manifold will need to be integrated into the existing control of the system. This is not a complex task but does normally require that two 'two core' and earth wires be routed back to the existing wiring system.
If the system is sealed then an extra expansion vessel may be required to cater for the increased water volume. The system must then be correctly flushed and an inhibitor added, Continental recommends the use of Sentinel X500, in order to prevent freezing and prolong the life of the system.
The final task with either option is to adjust the flow rates for any affected manifolds and check the system operation.
Continental Underfloor Heating has an expert technical team on hand to answer any questions. For more information log onto www.continental-ufh.com or call 0845 108 7001.
