hot rads when hot water on?

[persicus]

my brother in law recently bought a bungalow to renovate etc and decided in his infinite wisdom to hack all the central heating pipes out before i caould have a look at them, and then asked if i could "re-instate" them after he had finished kknocking all the walls down etc!

Anyway when i finally finished with new rads pipe runs and the like (plus a bit of guesswork) we fired the boiler up and when the hot water is on the radiators heat up (open vent system with a hot water cylinder, 3 way valve etc).

The original bathroom radiator (as far as i could work out) was connected to the "hot water side" of the 3 way valve (assume some sort of bespoke expansion vessel? so i connected the new one the same way (does the return have to be connected before any other rads?)
is this the problem or is it more likely to be the 3 way valve stuck? (you can manually move it and hear it)

he's not too bothered at the moment but i'm sure i put it back right and its bugging the hell out of me, also i want to explore all avenues before he forks out foa a new valve when its potentially not needed.

any ideas?

thanks in advance

 

[stem]

Connecting the bathroom radiator to the hot water system to dissipate excess heat is commonly found in systems that are (or were) heated by solid fuel with gravity circulation

The symptoms you describe could be the result of 'reverse circulation'. If you search you will find information about it. As you suspect it's caused by the incorrect sequence of connecting the returns.

This thread here contains an excellent diagram from ChrisR, if you scroll down a bit.

 

[persicus]

cheers chrisr

got mu bro to isolate the bathroom rad from rest of system and try the hot water again...........hey presto no heating up rads!

the bathroom rad wasnt the last return connection so im either going to make it the last return or just change the flow to heating side, (thats not going to cause anyproblems is it?)

 

[persicus]

sorry stem its your reply not chrisr!!!