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Feb 5, 2022
7
3
3
Gloucestershire
Member Type
DIY or Homeowner
Hi new to this forum, hope someone will have the answer to my issue.
I have Recently had a new Diverter valve brass body and motor replaced on my 15/19 Worcestershire heatslave oil boiler, due to the old one seized. Since this i have had issues with the water pressure in the boiler it drops to almost zero over 24 hrs period, once topped up via filling loop to approx 1.2bar (i have to do this everyday) i check it quite often during the day/evening and the pressure is sometimes as high as 2.3 bar. Could the guy who fitted the Diverter valve have fitted it back to front IE the A port to is to Central heating and B port is to hot water could it be wrong? Or is this correct. The boiler had no pressure issues prior to the Diverter valve replacement, definitely no leaks anywhere. I have no hot water on demand anymore since the valve replacement. I can Hear the flow switch operate when the hot tap is opened but the boiler does not fire up for hot water demand Until the slave tanks almost empty. Anyone have any ideas please.
I have added pic of the brass body with port markings this is the same as the one in my boiler.
 

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Sounds more like a failed filling loop, expansion vessel lost its charge or ruptured, or split in the plate heat exchanger to cause those pressure problems. First you need to get to the bottom of that and then look at any other problems that might be present.
 
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Sounds more like a failed filling loop, expansion vessel lost its charge or ruptured, or split in the plate heat exchanger to cause those pressure problems. First you need to get to the bottom of that and then look at any other problems that might be present.
Thanks for reply, why only since Diverter valve replacement though? Seems odd! The boiler was working absolutely perfect prior to this? Are the ports pipes from Diverter valve to the correct circuits? That is my main question?
The pressure vessel is approximately 18months old, i know it could of failed in that time.
I did wonder about the heat exchanger too??
Thanks again.
 
Honestly I haven’t touched a hestslave in some years but A usually is HW port. The manual for the valve if you have it would state which. The vessel could have failed or need charging yes and I suspect this is probably where the problem lies. The heat exchanger could have failed also but id imagine the pressure wouldn’t get to 2.3 bar if that was the case. Is it a condensing heatslave?
 
Honestly I haven’t touched a hestslave in some years but A usually is HW port. The manual for the valve if you have it would state which. The vessel could have failed or need charging yes and I suspect this is probably where the problem lies. The heat exchanger could have failed also but id imagine the pressure wouldn’t get to 2.3 bar if that was the case. Is it a condensing heatslave?
Thanks I’ll check the pressure at the vessel, I’m sure the plumber would of installed the D/V correct.
 
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You need to drop the pressure out of the system before checking vessel charge, otherwise you’ll get a false reading!👍
 
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If the picture you posted is the actual valve you have then it probably only needed a cartridge and not the body or head. Never known a head to go on those.

The cartridge sticks due to poor water quality.
You may want to look at a filter on your system if you haven't got one.
 
If the picture you posted is the actual valve you have then it probably only needed a cartridge and not the body or head. Never known a head to go on those.

The cartridge sticks due to poor water quality.
You may want to look at a filter on your system if you haven't got one.
Yes the motor was fine, I’ve kept for a spare, water is not great in this area, however it was the original brass body and the boiler is 15 yr old.. Would you happen to know if B port supposed to go to hot water side and A to C/H side??
Thanks
 
It's still young at 15.

Positioning of the valve body will have no impact on boiler water pressure.
That’s good to here the Mrs keeps going on about replacing it, I’m like why all parts are available, it’s just a case of getting to the bottom of each issue as they happen…
Thank for the reply👍🏽 I’m gonna check pressure vessel in the morning.
 
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Re age of boiler we probably on average rip out a leaking heatslave ever 3 weeks.
A good few of them less that 15.
One was only 4 years old ! virtually all leaking heat store tanks though a few leaking main hex.
 
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Re age of boiler we probably on average rip out a leaking heatslave ever 3 weeks.
A good few of them less that 15.
One was only 4 years old ! virtually all leaking heat store tanks though a few leaking main hex.
I had to replace my heat store tank a while back as it leaked but no. Red to replace the boiler…. To much of a throw away society these days.
 
I had to replace my heat store tank a while back as it leaked but no. Red to replace the boiler…. To much of a throw away society these days.
Well maybe if you can do work yourself. But if you have to pay someone to do it plus cost of parts.
You still have a 15 year old boiler that's obviously had/ got corrosion in the system.
A lot of customers would rather have a new more efficient boiler with a 5 year warranty or 10 year if they go for a blueflame.
 
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Up until my dad’s retirement and shortly before his death in 2015 we still had a few elderly customers with 30-40 year old boilers. I am a stronger believer in fixing what you can but they do not make boilers like they used to, that is a cold hard fact. Most modern day boiler manufacturers will only warrant their products up to around 12 years, beit gas or oil boilers and even then you have to satisfy a mountain of paperwork. If you can keep your boiler going for another few years then fair play and by all means do do but as I said modern boilers aren’t made like they used to be.
 
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