New autobypass valve failure?

[mike42]

Hi

I bought a Honeywell DU145 bypass valve (the righ-angled one) which is for when the frost stat in the garage where the boiler is kicks in.

I've only had it about a month and I'm sure when I first tested it it seemed fine. But now, even when I screw it in clockwise as far as it will go it still seems to leak water past it (the bypass pipe gets almost as hot as the flow from the boiler).

Has it broken already ? I hope I get a refund.....

Should I get another and if I do should I put a gate valve in series so that I can operate it manually if the second goes as quicky?

As ever, thanks for reading and thanks even more for replies

 

[mike42]

Was it a stupid question or maybe too dull or just people enjoying themselves over Xmas to worry about stuff like this?

ANother thought I had was maybe that whilst I was testing I'd left it too loose so it was open all the time and maybe that it got sludge/scale on it in that short time preventing it from closing? The system is full of sludge and seems almost impossible to remove despite chemical cleaning almost annually (and I can't afford a power washing machine). Maybe I'll find out when I take the valve out....

 

[stem]

Was it a stupid question or maybe too dull or just people enjoying themselves over Xmas to worry about stuff like this?

I don't think that is the case, lots of posts have been answered over Christmas, so probably it's not been answered because no one has a definite answer. Remember too those that give up their free time to help others are volunteers, so no one has a right to expect / demand an answer.

However, I will relate my experience and maybe it will help. I had exactly the same problem with a Danfoss valve, so, I took it back and got a replacement, still the same problem. Then when I looked inside, I could see that the valve consisted of a hard plastic disc, without a seal, held by a spring so that it rested against a ridge. It didn't fit tight, in fact, I could blow through it, but it did offer a significant resistance. So, I believe that the valve would always let by a small amount of water, not enough to cause a problem, but enough to make the connecting pipes hot to the touch.

 

[D_Hailsham]

What speed setting is the pump on?
Has the system been balanced?

 

[mike42]

I don't think that is the case, lots of posts have been answered over Christmas, so probably it's not been answered because no one has a definite answer. Remember too those that give up their free time to help others are volunteers, so no one has a right to expect / demand an answer.

However, I will relate my experience and maybe it will help. I had exactly the same problem with a Danfoss valve, so, I took it back and got a replacement, still the same problem. Then when I looked inside, I could see that the valve consisted of a hard plastic disc, without a seal, held by a spring so that it rested against a ridge. It didn't fit tight, in fact, I could blow through it, but it did offer a significant resistance. So, I believe that the valve would always let by a small amount of water, not enough to cause a problem, but enough to make the connecting pipes hot to the touch.

That's quite right, point taken and sorry if I came across that way but had to say something to "bump" the unanswered post a bit...
My Honeywell seems like a similar design so maybe its the same issue. Also once its been open for a while, then presumably grit etc could stick to the plastic disc thus preventing it from closing properly again?

The pump is set midway on 2 and the system not really properly balanced (I've tried before but with 21 rads its bloody difficult so I kind of do it "roughly" these days) . I normally set the abv with the heating MV closed and hot water MV on then slowly open until the pipe gets hot. I'm not sure thats right either though.