Boiler Problem

[Nigel C]

Hi Guys,
Having searched forum after forum and not found the answer to my problem I'm hoping that you kind folk have the answer to my problem. I have an Ideal Classic FF250 boiler about 10 years old that keeps tripping, i guess due to overheating. While this doesn't happen every day on the days that it does happen it sounds like a tank running through the house. The boiler has had the fan replaced which had been whistling. The plumber also replaced the water pump but believes that the noise is caused by sludge build up but seems reluctant to book us in for a power flush, maybe this is due to having microbore pipes but thats just my theory.
Having heard many loud clicks from the airing cupboard i checked the motorised valve earlier and it seems to me that the lever moves too freely and has no resistance. I don't know in what position the valve is stuck in, as due to its positioning i can't see the side with the lever. But I'm guessing its set to both CH and HW as when i turn the CH off and try HW only the boiler doesn't burst into life. My question is, would this faulty valve cause the boiler to trip occasionally and should i also consider changing the hot water tank stat just in case thats also faulty.

Many thanks for any advice given

 

[steve32]

Have you checked the area around the cold feed and vent with a magnet for blockages
I assume your system is ov

 

[Nigel C]

Hi Steve , thanks for the prompt reply. Yes it is an ov system and having checked every pipe in the airing cupboard with a magnet , especially around the cold feed I find that there is no build up for the magnet to stick to.

 

[Echo the husky]

Was the cylinder up to temperature when you did the hot water only test?

The valve doesn't switch the boiler and pump on for HW only, the programmer + cylinder stat do. The boiler and pump should still run, even if the water was being sent to the radiators instead, or going nowhere if there is a serious blockage. The valve may also be in the wrong position if the gears have broken in the valve actuator. If the lever is loose the valve is either in CH + HW or CH only positions. Depending on what was switched off last it may rest in either HW only or CH only.

 

[Nigel C]

Hi Steve, yes I believe the water in the tank was up to temperature as both heating and hot water were set to on at the time. The boiler though was inactive due to the room temperature being reached but the boiler still had not burst into life even after running 2 hot taps for approx 2 min, which I believe it should have.

 

[Echo the husky]

If the cylinder is hot it will often take quite a delay to get it to start again, just turn the cyl stat up until it clicks for the test, the boiler should instantly react.

 

[Nigel C]

Hi Freddo, having just done as suggested the boiler burst into life on hot water but the lever on the valve still remains easily movable. Am I right in thinking that the valve is faulty? And if so is this faulty valve the reason for my over heating boiler ? Or is that more likely a sludge problem. Despite no obvious magnetic material in the pipes.

 

[Echo the husky]

If you turn the Heating on (and the room stat up) the hot water on and the cyl stat up everything should run, then if you switch the heating off, the valve should be pulled to hot water only with it's internal spring, and the lever should then have resistance if you try to move it.

If it doesn't you have a fault with the valve actuator or the wiring or other heating/ hot water controls.

If you cut all the power to the central heating system at it's main switch, the valve should also spring closed. If it doesn't, the valve body/actuator is jammed in some way.

 

[Nigel C]

Thanks Freddo, I'm going to give that a try first thing tomorrow.Would this valve if faulty in anyway cause the boiler to over heat ?

 

[Echo the husky]

Shouldn't do, as either one or both ports will be open at any one time it will still allow water to flow. I'm electrical and more responding to the clicks coming from the airing cupboard and the loose valve lever on HW only. You say you can't see what position the valve is in as you can't see the side, I take it it has a plastic cover with a little indicator knob on the side to show what position it is in? The metal Honeywell ones don't have that useful feature.

For the overheating boiler, you'll have to ask one of the heating guys!

 

[Nigel C]

I'm not sure if it's Honeywell or not , it has a galvanised cover and all that I can read clearly is ' made in Canada' even if it's just the actuator due to the positioning of it it's not possible to reach the screws underneath the cover so would be regrettably easier to remove and replace the whole valve.

 

[Echo the husky]

Any photos? It should have been installed in a way that allows the actuator to be removed from the valve without disturbing the plumbing. Do the tests first though, it might be ok!

 

[75pete]

Made in Canada points to it being Honeywell.

 

[Nigel C]

Thanks, if the test proves its the valve I will try to post an image, but the cover is facing to the back wall of the airing cupboard and the space between the valve and hot water tank is not sufficient to squeeze between and I'm only average build.

 

[Nigel C]

Thanks 75pete.