Boiler or controls playing up

dl8860 · 9 Feb 2019 at 23:55

Have lived in my semi detached house for a bit over a year now. We have a conventional boiler, radiators, hot water tank type setup.

The controls let me put the heating and hot water on at different times of day, works well. For ages, when the hot water has been on, the radiators have got a bit warm too. Not a problem normally, during summer I just have the radiators set themselves to basically off, and in the winter it's not a problem to have a bit of extra heat.

Lately, the hot water has been playing up. The timer switches on on the controls, and the boiler fires up, but we aren't getting any hot water. It's like all the gas is being used to heat the radiators, I think they get hotter than they used to, before the hot water problems, but I'm not sure.

Just after we noticed issues, we starting using the manual 'advance' button, rather than relying on the timer, and that seemed to work. Today however I had the advance on HW for 90 minutes and we had basically no hot water. In the morning, there seems to be plenty of hot water, but I wonder if this is following having the heating on for 90 mins in the morning. So the CH may be 'leaking' into the HW, as well as the other way around.

Is it normal that the radiators get warm when the controls are saying HW on and CH not on? Is this a problem with my controls or the boiler? Or some other component? I grew up without central heating so don't know a ton about it, and it's really confusing reading about issues online.

I've booked an annual service from British Gas but that isn't until a week Monday. It'll cost me £90 for a callout from them to fix it, and even then that only covers if it's an issue with the boiler or controls themselves, not other components I believe. Would really like to get to the bottom of it myself if possible.

Thebug · 10 Feb 2019 at 06:33

Sounds like you have a valve stuck somewhere, like this

https://www.screwfix.com/p/honeywel...HEEFrBScR9cv5GMoyNwaAvw3EALw_wcB&gclsrc=aw.ds

Is

dl8860 · 10 Feb 2019 at 17:19

Looks like this is probably the culprit then? This is in my airing cupboard, that's the immersion heater on the left, boiler is downstairs.
I guess this is something I'd need a plumber or boiler specialist to replace unless I want to unleash a watery disaster. I can't see any model number or anything on it, or anything I can fiddle with or switch by the looks of it.

Quite minded to replace the whole system, don't like having non-combi boiler and we're thinking about redoing the bathroom anyway.

the_dead_parrot · 10 Feb 2019 at 18:34

Yeah that is likely to be the problem. Looking at the pump, cylinder thermostat and filter these are all British gas used / rebranded. The diverter will be a British gas re branded ACL Drayton 3 way valve. The little black piece on top should move corresponding to whether you set it to heat, hot water or both H M W. If it's not moving it may be the spindle from the brass body has seized or the motor in the head has seized.

You can remove the head without any water or issues. There is a black button underneath which you press in and pull the head away from the body. If the head then moves when you give it heat/water demand the body is the fault. There is a silver spindle which moves a paddle. Try moving it with your fingers, if it doesn't move the body has seized. It can be lubricated but is only usually a temporary fix.

Hope that helps.

dale1uk · 10 Feb 2019 at 20:00

As mentioned above the 3 port valve will be sticking. 99% of the time it'll just be the head that needs replaced. It's a simple job, just clip the old one off and then the new one clips on. No messing with isolating the water as you don't touch the main body. You will need to isolate the electrics and wire the new head in like for like.

Here's a link for a replacement Drayton 3 port head: https://www.screwfix.com/p/drayton-...VxE-h1vy6WEW3rkgKzYaAmmHEALw_wcB&gclsrc=aw.ds

dl8860 · 10 Feb 2019 at 22:16

the_dead_parrot said:
Yeah that is likely to be the problem. Looking at the pump, cylinder thermostat and filter these are all British gas used / rebranded. The diverter will be a British gas re branded ACL Drayton 3 way valve. The little black piece on top should move corresponding to whether you set it to heat, hot water or both H M W. If it's not moving it may be the spindle from the brass body has seized or the motor in the head has seized.

You can remove the head without any water or issues. There is a black button underneath which you press in and pull the head away from the body. If the head then moves when you give it heat/water demand the body is the fault. There is a silver spindle which moves a paddle. Try moving it with your fingers, if it doesn't move the body has seized. It can be lubricated but is only usually a temporary fix.

Hope that helps.

Thanks very much for this.

I've just detached the head and run a test, and the head unit is definitely operational and the valve doesn't seem to budge. How could I lubricate it? Would taking a pair of pliers to it to loosen it be a bad idea? I know you said it would be a short term fix, which might be fine as I might replace the whole system with a combi boiler anyway. Dumb question but this component definitely wouldn't be needed then right?

How much would I be looking at for replacement for this valve and head if I don't replace with a combi? I guess it means a whole system draining to replace that valve which I imagine isn't easy.

the_dead_parrot · 11 Feb 2019 at 09:59

dl8860 said:
Thanks very much for this.

I've just detached the head and run a test, and the head unit is definitely operational and the valve doesn't seem to budge. How could I lubricate it? Would taking a pair of pliers to it to loosen it be a bad idea? I know you said it would be a short term fix, which might be fine as I might replace the whole system with a combi boiler anyway. Dumb question but this component definitely wouldn't be needed then right?

How much would I be looking at for replacement for this valve and head if I don't replace with a combi? I guess it means a whole system draining to replace that valve which I imagine isn't easy.

It's a bit tricky to lubricate it especially when it's fitted facing the way yours is. I probably wouldn't recommend it. Instead just attempt to loosen it moving it backwards and forwards, if it's still stiff the valve or at least the paddle would need to be changed. Which would involve the cost of the part and draining etc.

If you change to a combi boiler this part or anything in the cupboard are no longer required. If your getting BG out anyway they do one off fixed fee repairs. Might be easier to just get them or someone else out as the position of the valve and draining probably take it a bit out of the DIY realm.

Just re read your first post. Do you already have a BG contract with an excess/call out fee? The diverter is classed as a control so would be covered.

dl8860 · 11 Feb 2019 at 10:54

I do have boiler and controls breakdown cover with BG, £99 excess and unlimited parts and labour, so that would be nice if the diverter is classified as control, I was starting to think it'd be seen as part of the central heating system so not covered.

I've just realised that the hot water tank has an electric immersion heater element so I've plugged that in and it seems to work. So I'll set that up on a timer, and that might even be more efficient to run than using the boiler to heat it, as we have econ 7 and I can set it to heat up during cheaper night hours.

So even if I am covered under the boiler and controls cover, if I'm going to switch to a combi and the electric immersion heater works in the meantime, that would be a waste of money. And if continues to work fine it becomes a much less urgent job.

dl8860 · 12 Feb 2019 at 08:34

So I've gathered 3 quotes this week so far.

One from a local boiler company, wife said she got the feeling they gave an expensive quote because they didn't really want the job, £3,714 including £400 boiler trade in discount and £250 off winter special. 7 year warranty.

Just had British Gas out this morning, £3,974 with 5 year warranty.

Another company quoted over the phone after asking lots of questions, £2,600 for 7 year warranty.

The first two seem very steep, the last one I'm worried is only less because they haven't come to visit and have a proper look.

Do these prices seem right? They seem really high to me.

dl8860 · 1 Mar 2020 at 22:41

bumping an old thread just in case anyone comes across this in a similar situation. got the valve situation sorted by a BG engineer, standard 90 quid callout or whatever. Far as I can tell/remember he just relubricated the valve and it's worked fine until recently. The central heating has been not clicking on reliably for a while, sometimes after a long time playing with resetting thermostat, turning the whole boiler and control off at the remains etc. I've been able to get it to fire. Have been thinking about replacing the thermostat system until I remembered about these previous issues, went and check the header unit (which before was working fine and the valve was stuck), and it's now that which is the issue, the switch won't move at all based off what the controls tell it, even when detached from the body/valve. Seems like the hard work it had to do previously with the stuck valve didn't kill it but probably weakened it and this winter has finally polish it off.

I've found a replacement on amazon for 49 quid so have bought that and it looks like it should be an easy fit myself, fingers crossed.