TRV's on bypass rads

[KJ1978]

Hello all

I have a bypass in my house which feeds two bathrooms, I've lived here 10 years and only recently realised these were on the bypass. I've always turned them off in the summer using the isolating valve fitted (not trv) as it would get too hot in the bathrooms. I'd like to fit TRV's to all rads including these two if possible. I believe that the rads are T'd off the bypass pipe because if they're closed the bypass pipe still gets very hot so I assume water is still flowing along it.. If I want to carry on turning these off in the sumer or fit TRV's should I fit a bypass valve to this pipe, or is it OK as is as the bypass pipe is probably quite long? It's a 3 storey house, boiler on ground floor and cylinder on top floor. The bypass rads are on the top floor and middle.

Another option would be to get a plumber in to fit a new bypass pipe between flow and return in the airing cupboard.

 

[rogerp]

Hi KJ1978,

From what you have described it sounds as though your bathroom radiators are piped into the primary circs which was once the standard for bathroom radiators or towel rails. This means that when hot water only is selected all radiators remain cold except bathrooms. What you are asking about a bypass is unlikely to have any bearing. All the bypass is, is a means to continue the flow in the system when 2 way valves have closed. When you say about making all valves trv, I would suggest that rather than a full overhaul to move your bathroom radiators to the secondary heating circs that you could fit trv's in order to close them during the summer. PLease be aware though that you do need to have a bypass radiator in your system which should be on the radiator wherever your roomstat is located.
Any further questions please ask
thanks RogerP

 

[KJ1978]

Hi, thanks for the response. I have a 22mm pipe in the airing cupboard that's marked as "bypass" but has no bypass valve fitted to it, there's no bypass valve visible anywhere on the system. That's why I thought the bathroom rads were connected to it. Otherwise it's just a length of pipe between the flow and return, not sure if that would actually work as a bypass.

The flow runs up the left hand side bends right then drops down, the bypass pipe T off the flow after the pump but before the zone valves. I was thinking of fitting bypass valve on this pipe.

Room stat is in the hall and no TRV would be fitted to that rad.

 

[KJ1978]

Here's a photo of the airing cupboard.

 

[TVP&H Ltd]

Do the bathroom rads get hot when just heating is selected?

 

[KJ1978]

No they get hot whenever the boiler fires, hot water & heating.

 

[kay-jay]

Sounds like someone messed up.
If your bypass is just a pipe joining the flow to the return it will be too effective as a bypass and the water will short circuit back to the boiler rather than force it's way through rads and around the system. Remember water is lazy. You need a valve of some description to balance the bypass with the rest of the system.
Re the rad in the hall as a non trv bypass rad. It depends if the rad us large enough. If not you may need an additional one as it needs to be sized in relation to system volume

 

[KJ1978]

Thanks kay-jay, I've lived here 10 years and had no problem with rads notgetting hot. I understand what you mean though the water will justfl flow along the bypass and take away from the water getting to the rads.

I do have a wheel type valve fitted to the return pipe as it comes out of the cylinder, this is marked up as "bypass valve do not adjust". I have been informed before that the late label is fitted to the wrong pipe. Picture below.

 

[KJ1978]

The central heating has been on for about 25 mins, the bypass pipe is as hot if not slightly hotter than the central heating pipe, so it would seem that a lot of water is flowing along it.

 

[kris]

Best to fit an automatic bypass valve,, get your system balanced then set the bypass accordingly, remove the gate valves altogether as waste of time, don't worry aboutvthe length of the bypass as longer the better,