I'm really hoping someone can offer some advice. I recently had installed a new oil heating installation. Its a large installation with 3 zones and water. All the zones have a shared return due to lack of space for individual returns for each zone, therefore a shared return for all zones has been installed. It now seems that when an individual zone is on in isolation, the water returning from the heated zone migrates through the return to the other zones which are off, causing the radiators in the zones that are switched off to heat up. My question is how can this problem be resolved?
Problems with a shared return on a new installation
- Thread starter melross
- Start date
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Why not get them back. There must be an error on the configuration. We cannot really answer the question without seeing at least a schematic of the plumbing. In fact, if you draw a schematic, you will probably see yourself how a circuit is being completed, and the solution
Agreed, need to check it still happens when there is no call for DHW. But it's hard to see how it can happen if the zone valves are closed.
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You can check if this is the case by feeling the radiator pipes. When a zone is working normally one pipe will be hotter than the other. If, when the zone is turned off, water is entering through the return, the roles will be reversed: i.e the hotter pipe will become the cooler and vice versa.
If that is the happening, a non-return valve on each return pipe will solve the problem. It prevents the water travelling the wrong way.
You could do that, obviously. But why not make sure that the plumber has not wrongly configured the pipework?. He may be perfectly amenable to admitting his error and rectifying. Why pay for time and materials to use a work around if doing it properly is possible?
And non return valves are restrictive and prone to sticking or collecting debris and blocking. In mains pipework that is not normally a problem, but could be in a circulatory system.
With regard to the HW being the last tee before the boiler, a quick schematic will explain the problem.
TBH, I have not done that type of work for many years, and was before multi zoning! I suspect the multiple zones makes it a bit more difficult to get it right, particularly if it is a changeover rather than a completete new system
Thanks
No it’s a brand new installation. No heating installed previously. When you say a wiring problem do you mean electrics?
Yeah control wiring of the heating system.
OK I will ask the Engineer to take a look at the electrics as well explore the other suggestions. Thanks very much for all your feedback. Much appreciated.
That's a problem with a non-zoned system, I had it in a new house in 1973, where the builders had installed the pipes wrong. The connection points were only about 1ft apart, but the effect, rads getting warm when HW calling, was quite marked.
But on a zoned system, assuming all zone valve are closed when no zone is calling, should it happen then?
any chance of a pic, or diagram, showing how the returns are connected?
None of what your saying makes sense.
If it’s not zoned why would it share a return pipe. Wouldn’t need to be shared. One flow one return because it’s not zoned.
It is zoned. Three zones and a separate zone for the water. It is the return that appears to be shared.
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