Boiler problems.

[John Brown]

I know there are some knowledgeable plumbers here, so maybe someone can help me out.
Our boiler, which serves the CH and the DHW, is showing an S30 status, which means no demand, when there clearly is a demand, as the house is below 10c, and the LED on the Wiser hub is on. My guess is that a motorised valve is sticking, and so the demand signal is interrupted by the MV limit switch. Does this sound plausible?
Unfortunately, I'm away in Devon for the week, but our daughter and grandkids are still in the house. I'm hoping that our friendly local plumber will get there today, but just trying to get my head round the problem in the meantime, in case I have to drive back and try to sort it.
I'm guessing it has two motorised valves, as the one that's visible has only two pipes attached.
Trying to work out if it's possible to override things in some fashion, as it's not the best time to be without heat, and I reckon the hot water tank would need to come out in order to swap the MV.

 

[Alli]

I know Honeywell type valves have a lever that you can override the valve and lock open, Assuming it's a motor problem rather than a microswitch problem I would have thought this might fire the boiler.

I don't know what make you have fitted but it might be worth your daughter having a look as its quite easy to talk through how to do it over the phone.

(I did this with my girlfriend just before Christmas, after delicately telling her, that it wasn't helpful having the camera pointing towards her face, try pointing it at the pipework so I can talk her through it )

 

[profchris]

One other thing to try, an easy one.

My own system sometimes drops out wifi between boiler and controller, as there are thick walls in between. Usually fixable by moving the (portable) controller nearer the boiler to re-establish the connection.

Also there is a box on the inside wall next to the boiler (my boiler is external) which receives the wifi. It has a green light to show the boiler is on, and a switch to press in which manually switches the boiler on.

If any of this applies to your system it might be worth a go.

 

[John Brown]

Thanks all. Plumber came and sorted it. It was a sticking motorised valve, as I suspected. Just hoping it doesn't happen again for a while..

 

[Richard_C]

Good that its sorted. If it happens often, most traditional Honeywell MVs let you change the head (motor-y bit) without drain down. A bit of a fiddle because they are often in awkward spaces but not technically demanding as long as you note which wires go where. Last one cost me about £20 but that was a few years back.

 

[Pedronicus]

Good that its sorted. If it happens often, most traditional Honeywell MVs let you change the head (motor-y bit) without drain down. A bit of a fiddle because they are often in awkward spaces but not technically demanding as long as you note which wires go where. Last one cost me about £20 but that was a few years back.

There are two types of Honeywell valve heads. The changeable ones have a embosed pimple on the top of the silver motor cover; the non-changeable ones (without a system drain down) do not have the pimple. DO NOT GET THEM CONFUSED as it can get very messy!

 

[John Brown]

Not even sure if they're Honeywell. Will take a look when I get home.

 

[John Brown]

One other thing to try, an easy one.

My own system sometimes drops out wifi between boiler and controller, as there are thick walls in between. Usually fixable by moving the (portable) controller nearer the boiler to re-establish the connection.

Also there is a box on the inside wall next to the boiler (my boiler is external) which receives the wifi. It has a green light to show the boiler is on, and a switch to press in which manually switches the boiler on.

If any of this applies to your system it might be worth a go.

Thanks, but I have the Drayton Wiser hub and "smart" valves. WiFi between hub and router, ZigBee or similar between hub and valves. A bit flakey in our barn conversion, but stumbles along as a rule.

 

[baldkev]

Have a good time in devon, dont forget to sample lots of cider

 

[XTiffy]

Just been through this exact problem. Sometimes it is the top, motorised section of a three port valve and can easily be swapped, but in our case the valve body was at fault. The plumber changed it without full draining down (used a vacuum cleaner technique to partially drain down). All working fine now.

 

[Spectric]

A bit of a fiddle because they are often in awkward spaces but not technically demanding as long as you note which wires go where.

Once electrically isolated cut the wires near to where it connects so you have the old wires remaining and then fit new valve head and just remove old wires one at a time and fit new one to its corresponding colour, much easier than just removing them all and then having to figure out which is which.

 

[John Brown]

I now have almost the reverse problem. The boiler is permanently on, as in firing up, running for a short period, pump overrun, anti-cycling, rinse and repeat, even though the heating is not demanding any heat. Am I right in thinking that this, also, could be the result of a stuck motorised valve?
I'll try to find a clear diagram of standard hot-water priority system wiring when I'm in front of a proper computer(grateful if someone could point me at one), but I'm speculating that the CH stat enables a motorised valve, and the limit switch on the valve enables the boiler. So if the valve gets stuck, the boiler stays on when the stat ceases to ask for heat.
Any thoughts?
Thanks in advance.

 

[XTiffy]

John Brown,
The attached wiring diagram and layout are pretty much what my own installation is. As I had a similar problem it was the three port valve. If you lift off the top section (lots of descriptions on YouTube), you should be able to rotate the valve (stem) by hand. If it is the valve itself (brass bit) at fault the system usually has to be drained down, though my plumber accomplished it by using a vacuum cleaner (no, I don't know how!) to partially drain down, then fitted new valve body and has been good since (fingers crossed).

 

[John Brown]

John Brown,
The attached wiring diagram and layout are pretty much what my own installation is. As I had a similar problem it was the three port valve. If you lift off the top section (lots of descriptions on YouTube), you should be able to rotate the valve (stem) by hand. If it is the valve itself (brass bit) at fault the system usually has to be drained down, though my plumber accomplished it by using a vacuum cleaner (no, I don't know how!) to partially drain down, then fitted new valve body and has been good since (fingers crossed).

Thanks. Ours is an 'S' configuration, rather than a 'Y', I believe. I'm now fairly confident it's a valve. Whoever installed this system should be hung, drawn and quartered. All the workings are behind the giant water tank. It's a nightmare!

 

[John Brown]

Yep, it's definitely the motorised valve. I don't reckon it can be changed without taking the tank out, so may have to live with it for a while.

 

[John Brown]

There are two types of Honeywell valve heads. The changeable ones have a embosed pimple on the top of the silver motor cover; the non-changeable ones (without a system drain down) do not have the pimple. DO NOT GET THEM CONFUSED as it can get very messy!

Any chance you could be more specific about where this pimple is? I'm working mainly by touch here, can't get a good view at all.

 

[Spectric]

Whoever installed this system should be hung, drawn and quartered. All the workings are behind the giant water tank. It's a nightmare!

Fully agree, just a bad design because any component has a potential to fail and should be accessable for replacement. I also would provide where possible an easy drain down valve for the system that drains to a drain, much easier than a hose.

You say it is an S plan, so you only have zone valves and no three way so has it been mounted in the right orientation so the head is above the pipe work.

 

[John Brown]

Fully agree, just a bad design because any component has a potential to fail and should be accessable for replacement. I also would provide where possible an easy drain down valve for the system that drains to a drain, much easier than a hose.

You say it is an S plan, so you only have zone valves and no three way so has it been mounted in the right orientation so the head is above the pipe work.

View attachment 153343

 

[John Brown]

Number 2 if bird's eye view, number 3 if viewed from the side. When I can get it to spring back, and then move the lever, it feels like the gears are worn. Waiting to hear back from my plumber - there's no way I can get my hands in there to change the head.
Incidentally, it is one with the dimple - I can just about see that now, so can be changed without draining down(except that it probably can't because of accessibility).

 

[John Brown]

Fully agree, just a bad design because any component has a potential to fail and should be accessable for replacement. I also would provide where possible an easy drain down valve for the system that drains to a drain, much easier than a hose.

You say it is an S plan, so you only have zone valves and no three way so has it been mounted in the right orientation so the head is above the pipe work.

View attachment 153343

By the way, is the fourth orientation a bad idea because of possible leakage?