Central Heating & Hot Water Issues - Help with Boiler Please!

JC9

Hi all - I haven't created a thread before, so hopefully this is in the right section of the forum!

We've recently bought and moved into a house and it appears we're having a few issues with the boiler, heating and hot water. I've no doubt it'll require an engineer to come and take a look, but I just want to get an idea of what the likely cause is so I can be a bit more clued up when speaking with them.

I'm not that great when it comes to plumbing and anything beyond average-skill DIY is out of my league, so I've tried my best to describe the issues below and include as many details as possible.

Problems:
1) Heating comes on when the hot water does. We set the hot water to come on for 20-30 minutes in the morning which is enough for our showers and water for the rest of the day. Unfortunately, the heating also kicks in and all of the radiators get hot. I think the reverse is also true; when the heating is on, the water heats up as well, but I'll have to double check that.
2) After about 10-15 minutes of the boiler being on (for HW or CH), it starts to cycle on/off every 90 seconds until the programmer turns it off at the set time.
3) The thermostat doesn't seem to work as I've tested setting it to 10 and the heating will still come on like normal and stay on until we turn it off manually.
4) Cylinder stat on the HW cylinder is pretty loose and I have to push it back in for it to be in full contact with the tank. Is there any method of securing it? It's also set to 70 which seems pretty high?

Model info:
Boiler - Ideal Classic FF260
Thermostat - Honeywell (possibly T6360-1028)
Programmer - Honeywell C27
Hot water tank - Albion 140L
Cylinder stat - Honeywell L641A
Photos - https://imgur.com/a/OslMH6R

Thoughts:
After doing some Googling, a few of the issues might relate to the 3-port valve failing or being wired incorrectly? Is there any way of checking this? Might also be worth noting that there is some pipework before the 3-port valve (but after the pump, with 2 inline gate valves) which feeds into the bottom of the hot water cylinder? Could this be bypassing the 3-port valve and rendering it useless?

If anyone could offer some advice on the above issues, that would be massively appreciated! Many thanks in advance.

Talldave

I agree it sounds like the motorised valve. It works on mains voltage so don't go probing unless you're confident. And anyway, if the valve is knackered you need a plumber to replace it (could be the valve body or the motor head that drives it). They would then test that calls for heat for heating and water are working independently and together.

AndyPK

yeah sounds typical of a motorized valve problem.

they cost about £50 + fitting.

yeah the tank thermostat needs to be in contact with the tank, to shut the boiler off when hot.

They can be held on with a white cord sometimes. (like a net curtain spring thing!)

Sort out those 2 issues and see what is left!

Gerry1

Could well be that the little synchronous motor has failed. It's a doddle to replace and they're available cheaply from places such as Screwfix. Just make sure you're competent working with mains voltages and take the appropriate precautions.

If you take the cover off the valve you may be able to open the valve by gently moving the main lever. There's often a latch arrangement so that you can leave it open. That will rule out an expensive problem with the plumbing. Similarly, you can remove the motor and connect it to the mains (more H&S warnings !) and see whether the little cog wheel rotates.

Just make a good note of how everything fits together because on mine I found that a plate could be installed upside down and its little lug prevented the valve from fully closing.

Talldave

Pop the programmer off its back plate and make sure the link that prevents independent HW/CH control is removed.

If the valve is wired up wrong, it'll never work. It it's wired correctly then I think it's jammed in the mid position because the return spring should return it to shut off the heating and if there was a motor problem you'd get hot water and no heating. From what you write it's stuck mid way and never moves.

Boiler cycling - not sure, is it overheating? Or is there an intermittent connection on the orange wire from the valve?

Search for a Y plan schematic.

JC9

Talldave wrote: »

I agree it sounds like the motorised valve. It works on mains voltage so don't go probing unless you're confident. And anyway, if the valve is knackered you need a plumber to replace it (could be the valve body or the motor head that drives it). They would then test that calls for heat for heating and water are working independently and together.

Talldave wrote: »

Pop the programmer off its back plate and make sure the link that prevents independent HW/CH control is removed.

If the valve is wired up wrong, it'll never work. It it's wired correctly then I think it's jammed in the mid position because the return spring should return it to shut off the heating and if there was a motor problem you'd get hot water and no heating. From what you write it's stuck mid way and never moves.

Boiler cycling - not sure, is it overheating? Or is there an intermittent connection on the orange wire from the valve?

Search for a Y plan schematic.

I'll avoid probing about in there as my electric knowledge is limited to lighting/switches and I wouldn't know how to test individual calls if I got that far anyway! I've attached a photo of the programmer wiring underneath.

Would moving the override lever to a different position show whether or not the spring or valve is working as intended? Also, do you have any idea about the pipework that is after the pump and before the 3 port valve? Seems like it would bypass the valve for some reason (haven't seen it in anyone elses heating systems).

If the boiler was overheating, wouldn't it trip the thermostat and I'd need to reset the button? That said, if we turn up the setting on the boiler (1-6), the higher we set it, the longer it runs before it starts cycling, so it could well be to do with the temperature? Sorry if I'm not giving great answers, but I massively appreciate the help

AndyPK wrote: »

yeah sounds typical of a motorized valve problem.

they cost about £50 + fitting.

yeah the tank thermostat needs to be in contact with the tank, to shut the boiler off when hot.

They can be held on with a white cord sometimes. (like a net curtain spring thing!)

Sort out those 2 issues and see what is left!

Fixed the tank thermostat in place with the cord, thanks for mentioning that, no idea why I didn't see it before! Any idea how much I'm looking at fitting wise? I'm in Worcester/West Mids if that makes a difference at all (I'll get some quotes anyway, but a ballpark figure would be nice to have). Thanks for the help!

Gerry1 wrote: »

Could well be that the little synchronous motor has failed. It's a doddle to replace and they're available cheaply from places such as Screwfix. Just make sure you're competent working with mains voltages and take the appropriate precautions.

If you take the cover off the valve you may be able to open the valve by gently moving the main lever. There's often a latch arrangement so that you can leave it open. That will rule out an expensive problem with the plumbing. Similarly, you can remove the motor and connect it to the mains (more H&S warnings !) and see whether the little cog wheel rotates.

Just make a good note of how everything fits together because on mine I found that a plate could be installed upside down and its little lug prevented the valve from fully closing.

I'd like to have a go at it, but my confidence with electrics probably isn't good enough and I'd be more scared of screwing anything up and having no heating at all!

Is there a position I could move the override valve lever to that would help diagnose anything? If I push it into the manual position, should that only give us CH and no HW? Thanks for the help so far!

Talldave

I missed the white cord for the tank stat in the pics when I initially looked!


The baseplate wiring looks standard, the pic doesn't quite show far enough down where the enable/disable independent control link goes - but I'm guessing that is not the problem.


I'm not a boiler expert, so cannot really advise on the boiler issue but from what you say, it sounds as if the boiler has its own thermostat which is causing it to cycle on and off. My personal, totally unqualified, view is that the boiler should be running at its max temp. You want maximum heat out of it to heat water and rads as fast as possible - the tank stat and the room stat shut it off when the requested temperatures have been reached. All that happens if you run the boiler at a lower temperature is that it takes longer to get water/rooms up to temperature.


For debugging, I use a mains test screwdriver with a neon light. They are ideal for probing the terminals in the wiring centre to check that the mains signals are appearing when they should be. Three outputs from the programmer are used: CH on, HW on, HW off. So, for example, with CH set to 24hrs and HW to Off on the programmer you get Live on the CH on and HW off outputs.


But I don't believe you have a wiring problem - if the boiler fires up with CH set to 24hrs and HW to Off on the programmer, then the microswitch in the valve is working, but if both output pipes from the valve are getting hot the valve is either stuck or damaged.


Similarly, with CH set to Off and HW to On (with tank stat cranked up) if the boiler fires up, then the wiring is OK. But if both pipes are getting hot, the valve is not closing off the A output.


The manual lever is used to manually move the valve against the spring that shuts off port A by default and allow flow through both ports (for filling/emptying the system). But as yours is stuck mid-way I'm not sure it's of any use; unless waggling it frees up whatever's stuck and allows the spring to return it to the port A closed position.


I would just get someone in to change it - job done. It's the weakest link in the system. The whole valve body & motor head is £90 at Screwfix, but they go for £30-£40 on ebay. I guess a plumber will charge full whack for the valve (£100+?) and labour on top. But if you were to obtain your own valve, then ask for fitting quotes, it might work out less - I'm not sure.

Scrounger

http://i.imgur.com/YwqGjYW.jpg

Out of curiosity, what is the grey cylindrical component low down below the pump (with 4 pipes)? (Click on the image to enlarge).

Thanks in advance.

Scrounger


Edit: found it - air separator

AndyPK

That white thing around the tank, is meant to be further up, and go around the stat, to hold it in

EDIT: Oh I see you have sorted that

AndyPK

one thing you can do with those valves, with the timer off....

remove the silver valve top. There are 2 gold screws under it IIRC.
Lift the silver block off.

You will then see a shaft which moves the valve. With a marker pen/tipex/paint. Mark the current position.

Then try moving it with fingers or plyers. It should only move a small amount. But how stiff is it? You should be able to move it with your fingers.

If however it is very stiff, or evidence of a small water leak then plumbing is required to change the brass block.

It moves from HotWater to middle (both) to Heating only.

return it to marked position before trying to refit the silver top

If it moves easily, then the silver top probably only needs replacement. (DIY electrical job)
It's a honeywell type. You can bid on them on ebay.
It maybe cheaper to get both the silver and brass items, in case the brass bit requires changing later by plumber

AndyPK

humm. more than £50 these days.

https://www.ebay.co.uk/itm/Boss-Therm-22mm-3port-mid-position-motorised-valve-Honeywell-Siemens-Equivalent/323938724970?hash=item4b6c40ac6a:g:rhwAAOSwolVdAO9C

https://www.ebay.co.uk/itm/Honeywell-V4073A1039-3-Port-Mid-Position-Diverter-Valve-22mm/163902326580?epid=2162824454&hash=item2629570734:g:UzwAAOSwZUFdoOlr

https://www.ebay.co.uk/itm/Honeywell-22mm-Mid-Position-Valve/113073245548?epid=1037646192&hash=item1a53b0cd6c:g:n~MAAOSwllpbJsCt

search for
honeywell mid position valve

don't get one that says, fits honeywell or replacement for honeywell
or equivalant

make sure yours says honeywell on the label first!