Hot water heats when heating turned on

Joined
5 Sep 2012
Messages
1,342
Reaction score
266
Location
Glasgow
Country
United Kingdom
Hi,
My hot water cylinder heats as it should when the hot water is on, but also heats up when the hot water is off but the heating is on.

I have a maintenance contract and the guy came and fitted a new actuator (the old one was working anyway), freed off the valve that the actuator clips onto (by working it off/on with pliers), and when checked it seemed ok. A couple of days later it's back the same. I've verified the actuator moves according to DHW settings, and the valve seems fairly free to move using just my fingers, and moves maybe a little more than an eighth of a turn. Obviously I can/will phone them out again but it's a bit of a pain to plan being in all day. Now the sceptical part of me says maybe the valve should have been replaced on the first visit but maybe the guy was being lazy and couldn't be bothered draining the system, so I'd like a little more knowledge before calling them back out. So...

Is the valve ok, ie should it move more than an eighth of a turn?
Would it require a (partial at least?) drain down to swap it over?
Should the pipe "after" the valve be warm when the valve is closed? (I understand some heat will pass up the pipe, mine is a bit hotter than that).

System is about 14 years old, gravity fed from small tank in loft. It was flushed and inhibiter added (by me) about 3 years ago. Rads were also removed and flushed with garden hose - no crud but a little black water. House is on two levels, cylinder in upstairs cupboard.
Thanks for any help :)
 
Take the head off, close the valve to HW and fire the boiler up. If its passing it'll need a new valve body. It will get hot through convection. Plumber wasn't necessarily being lazy, if it worked while he was there why go to the bother/expense of doing work that might not have needed doing. If everyone just changed the full valve on a whim your premiums would sharp go up.
 

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

 
Back
Top