Domestic hot water cold but central heating ok

10 Feb 2010
Reaction score
United Kingdom
I have a fully pumped central heating and domestic hot water system operated by separate motorised valves. The central heating works ok but the domestic hot water pipes are not heating up. The bolier is ok; the control programmer is ok, the cylinder thermostat is ok; the motorised valve is opening and closing ok but the return flow pipe just does not get warm / hot. I've drained and refilled the whole system 3 times thinking that I must have an airlock but I still have the same problem; central heating radiators fill, bleed and heat up ok. I can only think that I have an airlock that I can't shift!!! Any ideas?
Sponsored Links
is the boiler firing up on hw only ?
did you open the mot valve when refilling ?
Sorry for the delay in replying, I've had problems with the website.

Motorised valves were open when system was draining and refilling.

I tried HW by itself and presumed boiler fired up as the flow pipe heated up but the return pipe remained cold; didn't even get warm.

DIYnot Local

Staff member

If you need to find a tradesperson to get your job done, please try our local search below, or if you are doing it yourself you can find suppliers local to you.

Select the supplier or trade you require, enter your location to begin your search.

Are you a trade or supplier? You can create your listing free at DIYnot Local

Sponsored Links