Hot water/Cold rads

kay 9

Hi all, first time poster in this section, Looking for some advice on a heating system, I will explain all as clearly as I can to help others to advise and so on. Here goes...It's an open vent system (Oil Boiler) and I replaced all existing rads with new ones and put a new manifold on both the flow and return. I flushed all out prior to this after taking down the old rads. The flow and return from the boiler has a Tee directly at the back which goes to an extension of the house to heat two rads, both which are fitted with Trvs. That side has the pump on the return. Then the other side of the Tee goes to the Hot water cylinder and to the flow and return manifolds. Theses pipes to the manifold are run across the attic with the expansion on the flow. I have fitted 2 auto air vents fitted at the highest point in the attic and have the pump fitted on the return. Then vented all. Proceeded to switch on the boiler and after a short period of time the cylinder flow pipe gets extremely hot and the cylinder bangs. To my knowledge I have the pumps fitted correctly. I have even tried it on the flow but to no avail it was then taking water from the rads due to too much negative pressure I presume. The system has been put back together as it was exactly and the only conclusion I can come to is an airlock somewhere in the sytem or one of the pumps is not working maybe, although they are vibrating but have heard this is not a dead cert that they are funtioning properly (Worn out impellers) As said the only changes made to the entire sytem is 2 new manifolds as the prior ones were a homemade brazed job and changed the rads, most are smaller as they have a higher output anyway. Added 2 auto air vents and thats it.

Any help is greatly appreciated folks, Thanks again:)

oxygenman

Can you isolate the cylinder and see does the water heat the rads?

kay 9

I can't too easily as there is no isolating valves or even a balancinng valve on the cylinder. I'll drain it down again and try isolate the cylinder and see what the story is. It's beginning to get to me though this one. As all is done the exact same way etc. thanks for the reply though.

oxygenman

No bother, let me know how you get on...Gis a job :D:D!!!

kay 9

How ya Oxygen man, Got that sorted, Changed the cf to the flow. They had it in the return. Pitching stopped and pullin from the rads. Alls working even now. Thanks mate.

oxygenman

Glad to hear