A classic with a twist - no HW, CH OK, conventional boiler

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giraffeonastick

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Hi all,

Here out of desperation. Had a new bathroom fitted and the system was drained down to fit a new radiator on our ageing Potterton F60 on a conventional gravity fed system.

For a week I've had no HW through the boiler (had to revert to immersion (however that's spelled)). Rads all fine and boiler fires up OK even when I put the HW on.

To date to try and troubleshoot (because fitter's plumber can't come for another couple of days) I have:

1) Powered off all electricity to the system (read that sometimes that can reset the electromagnet in the 3way diverter).
2) moved the 3 way diverter to Manual (and clicked into place. First time I did it, it moved back to auto. Does this suggest a problem?)
3) checked the F&E tank - it has water in it. Pushed down on the ball to add a little more just in case
4) with the diverter on manual - ran HW only. Rads all got hot, still no HW

Suggested to fitter that the HW coil may have an airlock - he thinks not.
Question: would I still be able to get water from the HW tap if this was the case, and would an airlock in the coil prevent the immersion from working too?

Another Q: when I was looking at the F&E tank - I noticed that it was wet around it. It's never been wet before. What would cause that? (other than a leak in the joint)

I'm at my wits' end and can't afford to run the immersion daily, not to mention the inconvenience of having to get up early and put it on. If anyone can suggest the next step to try before I call my own plumber (at considerable expense, I fear) - I'd be very grateful.
 
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Air in the coil is likely, this would not have any effect on the immersion or water from the taps.
The other possibility is the valve has stuck in the CH only position.
 
Photo's are always useful. ;)

If CH is working ok, then the problem lies with water not getting around the HW circuit. When moving 3 way valve to manual, do you find resistance, and/or hear the workings 'whirr'? (Make/model of valve can be handy, some are more troublesome than others.) Try running system on HW only, what happens? Switching heating off with HW on and calling then you should see or hear valve operating to close off the heating port and put flow through to HW.

Simple, maybe silly things but rule the blindingly obvious out first! Cylinder stat is turned up and calling for heat? Balancing valve on HW return (if fitted) is open enough to allow flow? If there is an air bleed fitted to the HW coil circuit, this is bled and all air released. (Bleed with system off or pump can push water out giving false impression.)
 
Ahh thanks.
I'm an absolute noob with these systems; I'll get some photos. It's a Honeywell diverter valve - can't get in to see the model - but it must be 20yrs old. There was some resistance felt when moving to manual - with everything switched off I could hear the mechanism moving ('whirring') as I moved the switch.

[GALLERY=media, 96950]Honeywell Diverter3 by giraffeonastick posted 21 Jan 2016 at 1:32 PM[/GALLERY]
[GALLERY=media, 96949]Honeywell Diverter2 by giraffeonastick posted 21 Jan 2016 at 1:32 PM[/GALLERY]
[GALLERY=media, 96946]Honeywell diverter valve by giraffeonastick posted 21 Jan 2016 at 1:32 PM[/GALLERY]
The last pic might show the arm back at 'auto' - it's currently on 'manual' though.

Ran the system for an hour on HW only this morning - rads got hot, no HW produced.

Cylinder stat - is that the temp on the water cylinder in the airing cupboard? That's at 60.

The balancing valve - now you've got me - is that in the airing cupboard too? Ditto the HW coil circuit - I can't identify which one that is. Pic of a/cupboard:
[GALLERY=media, 96947]airing cupboard by giraffeonastick posted 21 Jan 2016 at 1:32 PM[/GALLERY]

and under the tank:
[GALLERY=media, 96948]pump, magnaclean and diverter valve by giraffeonastick posted 21 Jan 2016 at 1:32 PM[/GALLERY]
 
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I
giraffeonastick said:
I'm at my wits' end and can't afford to run the immersion daily, not to mention the inconvenience of having to get up early and put it on. If anyone can suggest the next step to try before I call my own plumber (at considerable expense, I fear) - I'd be very grateful.
Click to expand...

If you can afford to have a new bathroom fitted then the small cost of heating water with the immersion heater will be peanuts.

And well covered by your saving by not running the heating.

If its correctly set you can leave your immersion heater on all the time. It has a thermostat and that turns it off as soon as the water reaches the set temperature.

Tony
 
Agile said:
If its correctly set you can leave your immersion heater on all the time. It has a thermostat and that turns it off as soon as the water reaches the set temperature.

Tony
Click to expand...

Thanks Tony, there are a lot of scaremongering stories out there.
Please don't assume that because I have had a new bathroom fitted I'm made of money; it was a gift (but you weren't to know that) from well-meaning family.


Post edited further up with pictures.
 
Honeywell usually good valve. but at that age, possible its faulty. However, opening it to manual and I'd expect both HW and CH to operate, albeit with no thermostatic control other than the boiler stat. However, current symptoms do seem to suggest valve has stuck open to CH.

Cylinder stat is at correct setting by sound of it, look at the 2 pipes that connect to the side of the cylinder, on the R/H side in your picture, one about half way up, the other directly below, near the bottom. Is that gate valve open? (Not sure why its there by hey ho...) Secondly, the bleed on the top of the 15mm pipe sticking up. With system off, open it gently, do you get water from it?
 
This is really helpful, thanks all for taking the time to reply. I'm asking so that when someone eventually turns up to check it, I'm not being sold up the swanny with a "oh you need X Y and Z". I think it's pointing to the Honeywell being stuck and probably needing to be replaced, but I want to be informed and not cheated.

The gate valve on the R/H side was half-open, I've opened it fully - what does it do? (just out of curiosity)

Re the bleed - do you mean on that random pipe (1) or off the top of the cylinder (2)?
1 and 2.jpg
 
1 is the air bleed, this will vent any air collected from the coil inside the cylinder. If this pipework is full of water then point to valve being suspect.

2 is the outlet for the domestic hot water, it enters the tank on the L/H side at the bottom, supplied from storage cistern in the loft, and goes from the top, pipe going to the left will be the vent over the cistern, and to the right to supply hot taps. This is completely separate from the CH water (that should be!) circulating through the coil inside the cylinder.

If HW only is selected on the programmer, does the pump operate?
 
Yes - everything springs to life and sounds pretty normal - pump operates, things get hot under there.... then the rads get hot but no HW comes from the taps (tested with an hour of running HW only this morning).

I'll test the no1 bleed bit later on as I can't find my rad key at the moment. What will I gain by bleeding that - would it remove any air from the system to allow the HW to work again?
 
It'll prove a point. ;) If the cylinder coil is full of air, then that could prevent the water from circulating and heating the cylinder. It's just to rule that out. I'm suspecting a faulty valve, but checking the easy options first.
 
Super, thanks. I think I am beginning to conclude the same as you.

Just found the key and finished bleeding that valve - just a little bit of air in it.

Out of interest - I'm in Scotland (so not London prices) - what's a ballpark on how much these valves are to replace, please?

Heating and HW came on (timed) - the rads seem to have a lot more air in them (this entire system is riddled with air at the best of times and we bleed rads regularly), quite a lot of noise in the rads when it sprang to life.

Out of interest, what valve would you recommend replacing this with (this is an open Q to any engineers reading)?
 
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give it a try. Water should squirt out freely.

Is the top of the cylinder higher than the highest radiator in the house?
 
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