Can I tell if my boiler has a bypass fitted?

[Michael D]

I had a new boiler (Potterton 80 combi) fitted about 5 years ago & had TRV's fitted (on all radiators) at the same time. Subsequently someone said to me that I should have at least 1 radiator without a TRV. When I mentioned this to the British Gas engineer doing my annual service during the summer he removed the one from my bathroom (he didn't seem to check whether or not I had a bypass).

The problem now is that my bathroom is very warm - uncomfortably so at times, so I'd like to put the TRV back on. As I don't actually know for sure whether or not I've got a bypass fitted I don't know whether I can safely put the TRV back on. As the pipework around the boiler is boxed in I can't tell if there's a bypass there without slightly trashing the 'boxing-in'.

Any advice on whether or not it's likely I've got a bypass or how I could find out would be useful.

Many thanks,

Michael

[Set Square]

There seems to be some muddled thinking here! The idea of having one radiator without a TRV is that you must *also* have a room stat in the area served by that radiator, which switches the *whole lot* off when it gets up to temperature - otherwise known as a boiler interlock.

Have you got such a room stat? Without it, there was no point whatsoever in removing the TRV!

Whether or nor you need a by-pass depends on a number of factors. Does your boiler have a pump over-run stat, and is the pump connected to it? Do you have an S-Plan (2 x 2-port zone valves) system or a Y-Plan (3-port mid-position valve) system? If the latter, and if one rad is always on, there should always be a flow path open - thus not needing a by-pass.

[Ed Sirett]

What do the installation instructions say? A way of implementing a bypass is to have a permanently open radiator although dedicated pipework with a gate valve or pressure sensitive bypass valve is better.

[Christian McArdle]

Very unlikely, as it is a combi boiler...

Christian.

[Set Square]

Fair point - I had overlooked the "combi" reference. It is likely, therefore, with no zone valves and one permanently-on rad, that a by-pass

*isn't* required.

I was more concerned (in the part of my post which you didn't quote) with the fact that a TRV had been removed, but that there was no mention of a room stat.

[Christian McArdle]

Indeed, although it might be better to switch the TRVless radiator to the lounge. A room thermostat in the bathroom could be less than ideal.

Christian.

[mike ring]

"Christian McArdle" wrote in news:41824627$0$2292$ [e-mail]:

As long as there isn't a gas fire in the lounge, like mine.

(Apologies to respondents, but it may not be that obvious to the OP)

mike

[Michael D]

Thanks for the replies - I haven't got a room stat, either in the bathroom or in any other room... which is obviously why the room's getting so warm. I'd like to put the TRV back on, but I don't want to if it's going to cause problems if I don't have a bypass fitted (I seem to remember that I did have a pump go about 18 months ago).

The installation instructions for the (Myson) TRV's say that a bypass should be fitted - the problem is that I don't know if there is one.

The plumber who fitted the boiler fitted the TRV's on all the radiators (at the same time as installing the boiler). I don't know if that means that it's fair to assume that it's very likely that he would have fitted a bypass.

Regards,

Michael

[Dantb]

Doubt he's bothered. He shouldve supplied a room star at least and had the bypass rad in same room, often hallway.

[ARW]

17 years old.

FFS