Truma automatic dump valve question with a twist

[solaris]

The twist is that when opened only about a litre of water drains out. Tend to go away for a few days every other week and at this time of year drain down between trips. First noticed when on refilling the system came up to pressure in seconds rather than the wait for filling the boiler, a Truma combi. Next drain down put a bucket under, open valve and about a litre came out. About 10 minutes later the rest suddenly drained. This time again about a litre but it’s been left open for a day and no more water has come out. If I turn the pump on it pumps water out but stops when pump is turned off. Taps are opened as usual. Think I might change to a manual dump valve but is the problem likely to be in the boiler?

 

[Bessy765]

Our Burstner has the same dump valve as yours but hidden away behind it is the manual (valve with a yellow lever??)

 

[Lenny HB]

Think I might change to a manual dump valve but is the problem likely to be in the boiler?

Disconnect it and see if it drains properly then.
If you change to a manual valve you will have no protection if the temperature drops and you haven't drained down.

 

[68c]

I disconnected the leisure battery, later I was running the pump to wash my hands when a neighbour came across to say water was pouring out from the boiler drain. It seems the valve opens if no 12v supply. It was summer so not caused by cold. Not a hundred percent sure but could see no other reason why it opened.

 

[Lenny HB]

I disconnected the leisure battery, later I was running the pump to wash my hands when a neighbour came across to say water was pouring out from the boiler drain. It seems the valve opens if no 12v supply. It was summer so not caused by cold. Not a hundred percent sure but could see no other reason why it opened.

That is the older frost protection valve, vans with the C4 or C6 Combi have a manual frost valve from around 2008.

^{_{Subscribers  do not see these advertisements}}

 

[solaris]

Thanks for comments. System has worked fine for 3.5 years. Valve is modern mechanical one compared to the older electrical version which could also have been triggered by disconnection from 12v or low battery. Funnily enough that was all mentioned by helpful chap at Webbs Tilehurst who also demonstrated how to use quick fit connections. His bet was a bit of gunk in valve, wished me luck with balance of content of boiler when I disconnect valve. As I have no leaks and system works fine, apart from this problem I’m going to leave it for a couple of weeks till after our next trip. Have to do some dismantling for easier access. Will keep van heated in meantime

 

[68c]

That is the older frost protection valve, vans with the C4 or C6 Combi have a manual frost valve from around 2008.

Can I retrofit the mechanical valve in place of the earlier electric operated one?

 

[Lenny HB]

Can I retrofit the mechanical valve in place of the earlier electric operated one?

Yes but they are about £125.
You would need to do a bit of plumbing as they need to be mounted on the floor, different versions available for flexible or push-fit pipes. They are better because they don't open until it drops to 3°.

 

[solaris]

From looking yesterday think they’re closer to £150. I’ve had both automatic and manual valves previously. Always thought there’s an inherent danger on relying on an automatic dump valve as whilst it may protect boiler if the temperature drops really low it still leaves the pipework and taps at risk. Although cheaper than the boiler, still inconvenient. Easier to keep a cautious eye on weather forecast

 

[autorouter]

deleted

^{_{Subscribers  do not see these advertisements}}

 

[mapman]

When I drained down a few weeks ago I had the same issue. Only a partial drain from boiler - presumably sufficient to allow expansion of rest. On the Weinsberg there are 2 further valves in hot and cold supplies on floor under sink/cooker. Last year opening these resulted in more water being drained off, but this year no where near as much. Tried running pump but still not convinced boiler has fully drained. So decided to put a bar heater next to boiler until I can investigate further.