Worcester Heatslave 15/19 Problems

[pandr]

We have a Worcester Heatslave 15/19 oil combi boiler which has been working fine since we moved into the house in May.

This morning we woke to no hot water (heating is switched off anyway) and found the power light out on the boiler. Investigating I found that the fuse inside the boiler on the circuit board had blown and so after going to buy a new one I replaced it and the boiler powered up but didn't make the usual noises it does when heating (assume therefore not firing).

I noticed that there is a pressure gauge which was on 0 and after some searching on here I found that I may need to add pressure which I did using the valve on the flexible pipe on top of the boiler to reach the desired setting just above 1. After turning the boiler off and on again, nothing happened with both HW and CH on. I then tried the reset switch under the control panel and the boiler fired up and the CH kicked in with rad getting hot, however no HW.

I waited for around an hour and still no HW. Then noticed that the pressure had risen to above 2. Tried turning the boiler off and on again but now no CH or HW and the reset button does nothing. I have tried releasing some pressure by bleeding a rad until pressure shown at correct level. Still no CH or HW and boiler not firing.

I would really appreciate any advice or direction on what to try next!

Thanks

P.

 

[Burnerman]

If the boiler can provide heating but no hot water then there's a good chance that the diverter valve has called it a day.....this directs hot water to either the heating circuit or the heatslave tank, depending on demand. Maybe when this packed in it took the fuse out too?
The diverter is above the water pump, boiler front off, and it contains a stepper motor which operates the valve itself.
At the same time, its worth bleeding the valves on the top of the boiler (3) to see if any air is present, and have the red expansion vessel checked for air pressure at the same time. (10 psi, with no pressure registering in the system.)
John

 

[Terrywookfit]

If the boiler can provide heating but no hot water then there's a good chance that the diverter valve has called it a day.....this directs hot water to either the heating circuit or the heatslave tank, depending on demand. Maybe when this packed in it took the fuse out too?
The diverter is above the water pump, boiler front off, and it contains a stepper motor which operates the valve itself.
At the same time, its worth bleeding the valves on the top of the boiler (3) to see if any air is present, and have the red expansion vessel checked for air pressure at the same time. (10 psi, with no pressure registering in the system.)
John

It's a "Synchronous motor" not a "Stepper"motor!!

 

[oilboffin]

Yes indeed also just take off the motor wiggle the valve then with power off work the motor
sow times they'll work for a while after this

 

[Burnerman]

Shoot! You're absolutely right.
John

 

[pandr]

Thanks for your replies!

I only had HW for a short time and since then neither.
I have since tried bleeding the motor after which the boiler fired and we have HW for a few seconds before it stopped again.

From your replies I take it I should next try bleeding the three valves on the top, but I'm not sure which these are, what should I be looking for?

Thanks

 

[pandr]

An update: it seems that when the boiler is off for a while (i.e. an hour or more) and then switched on, it fires and we have hot water for a few minutes. After this it reverts to the issue where on turning on the heating, or hot water tap, nothing happens.

Thanks again for your advice and ideas.

 

[Burnerman]

With the boiler top off, look for three bleed valves, square, very similar to a radiator bleed. Just crack them open one at a time, just to see if there is any air around.
When you turn on a hot tap.....can you hear a click from the flow switch, top of the boiler, on the incoming cold pipe?
Make sure that the overheat trip, under the front panel left side, doesn't need resetting - press it upwards.
Presumably the PCB fuse hasn't blown again?
John

 

[Terrywookfit]

Is the burner lockout light illuminating.

 

[pandr]

Thanks I will try those valves.

When turning on the hot water tap there is a click as in usual operation, but not the sound of the boiler firing up. There is also a click when the tap is turned off.

The PCB fuse is ok and the trip doesn't need resetting. The lock out light has not illuminated.

Thanks, off to try bleeding...

 

[pandr]

Of the three valves on top, two are on pipes and one on the side of what looks like the main unit (?). This third ones turned and a lot of air came out. The two on pipes are quite corroded and won't turn - I'm using pliers and at risk of breaking them.

With so much air released from one I tried the hot water again but no luck...

 

[Burnerman]

Air needs to be released from the pipes, the one you can open sounds like its from the top of the heatslave tank.
As the burner lockout lamp is off, and the reset presumably has been reset (!) then the thermostats need to be calling for heat.
Don't forget, when air is released the boiler pressure will reduce, but that shouldn't stop the thing from firing up.
How about the PCB fuse - is it still intact?
John

 

[pandr]

I finally managed to get the valves open and released some air (although not much), I've bled everywhere else again (including radiators). When the boiler has been off for a while and has gone cold, when switching it back on it fires up for a few minutes but after that still does not come on when the hot water tap is turned on, although it does click (seems to know hot water required).

What should I try next??

Thanks so much for the help and advice

 

[Burnerman]

At this point, how I wish the others would chip in
As soon as the hot tap is turned on, the flow switch clicks and the burner should start.....it seems like there is no problem with the burner so far.
Are you able to check for continuity across the flow switch terminals?
Also, have you spotted the brass automatic air valve on the top of the boiler (with a car valve cap on) - does undoing the cap release any more air?
John

 

[ianmcd]

Ha Ha its your baby now John until Tony comes along