RAVENHEAT CSI 85 COMBI BOILER, PRESSURE KEEPS DROPPING?

Hottub · 21 Mar 2007

Hello all,
I have recently had lots of trouble with my Ravenheat boiler, recently changed the diverter valve then worked fine for a couple of weeks, however now its playing up again!
The pressure keeps dropping down, last night I filled the system to 1.5 bar however it had dropped to 1 bar this morning and the boiler keeps cutting out, when filled to 1.5 bar and heating and water turned on the boiler fires up and fan starts and boiler works ok however after 1 min it goes back out? But sometimes works fine for the whole evening?
Only Sometimes the red light and a rest is needed however most of the time it is not needed, I think the red light only relates to air in the system which will be the case because I do have to keep filling it up.
I had a corgi reg company have a look but all they wanted to do was charge £170 for a new board, if I need a new board then fine but this was diagnosed by them guessing and not doing any kind of checks whatsoever, Im no expert but there must be some way of checking from point to point to rule things out before replacing expensive parts.
Does anybody know what this fault sounds like it might be? Also I might change the DHW Sensor first as its relatively cheap compared to other items.
Thanks Wayne

Timmyturtle · 21 Mar 2007

If pressure is dropping that indicates a leak.
Have a look at the pressure relief pipe that terminates (usually) outside.
If it is dripping it could be the pressure relief valve letting by
Just changed one of those on a Ravenheat boiler.

Hottub · 21 Mar 2007

If pressure is dropping that indicates a leak.
Have a look at the pressure relief pipe that terminates (usually) outside.
If it is dripping it could be the pressure relief valve letting by
Just changed one of those on a Ravenheat boiler.

R that sound like it! I did not notice any leaks inside the house anywhere even under boiler, however I have noticed outside down the wall where the pipe comes out a green water line recently appeared.
Ive not noticed it wet but ill run the boiler tonight and see if i can spot it drippng, if its the pressure relief valve do you know if this is something I could change myself?

Many many thanks Wayne

Timmyturtle · 21 Mar 2007

That all depends on your skills really.
The one i did was .
release pressure from system(did through relief valve as leaking anyway)
undo 1 nut and 1 small allen screw , with bucket/tray/catcher to hand
pull out from housing ,fit male iron(brass) from old valve to new valve with ptfe or similar
fit new to boiler and tighten nut/screw
This was obviously the o`ring type though similar procedure for other one.
Its worth noting the one i did was a clogged boiler that had discharged some crud , which had damaged the relief valve seal(soon to be powerflushed/possible boiler change)
Valve cost approx £15

Hottub · 21 Mar 2007

I think thats the part that was undone a few weeks ago to replace the diverter valve.
Its got a red plastic front with a allen key hole on the side and bleed nut underneath.
I wonder if the guy who changed the diverter valve has left this open, ill check and if its shut ill drain the system and change this and the D.H.W / C.H Sensors also and cross my fingers!
Once again many thanks! Wayne

Timmyturtle · 21 Mar 2007

If its serviceable it should automatically close (spring loaded)
Yes it has a red knob

Hottub · 21 Mar 2007

O.k. thanks, lps supplies.com have a CSI 85 Safety Relief Valve for £9.93
it looks like the right one ill check the part no.
thx Wayne

Hottub · 22 Mar 2007

If pressure is dropping that indicates a leak.
Have a look at the pressure relief pipe that terminates (usually) outside.
If it is dripping it could be the pressure relief valve letting by
Just changed one of those on a Ravenheat boiler.

I had a look last night with the boiler running but the pipe wasnt dripping but the flue was steaming and dripping constantly!

however this morning the flue wasn't dripping but the copper pipe that exits the boiler and comes out the wall was dripping!

and last night when the boiler packed up again after a few hours of working it did need the thermostat resetting?

Does this still sound like it might be the pressure relief valve ?
Many thanks Wayne

Timmyturtle · 25 Mar 2007

It could be the pressure relief valve,however if it isnt always leaking from discharge pipe it could be an expansion problem
Has the expansion vessel got the correct pressure in it when the heating pressure is released.Cant think what you call this pressure
basically the vessel is pre-charged with air before it is fitted,it needs this air pressure to take up any expansion

Slugbabydotcom · 26 Mar 2007

If you set the pressure to 1.5 when cold what is the pressure when the heating has fully warmed up ?

Hottub · 26 Mar 2007

Its around 2- 2.5 bar when its been operating for a while.

Slugbabydotcom · 26 Mar 2007

First thing to do is sort your pressure vessel out then. Try pumping it up first. I think theres some instructions in the FAQ

Hottub · 27 Mar 2007

I found the valve for the pressure vessel, (just like car tyre valve) but when I pressed on it there was high air pressure but no sign of any water.

Last two nights pressure hasnt dropped, Im now wondeing if it could be a board as there is so much intermitent mucking around.

Slugbabydotcom · 27 Mar 2007

The fact that your pressure rises more than 0.5 bar means that it does require some attention. It may work for the time being but 1 bar increase is the harbinger of trouble. It won't be long before your PRV starts leaking again

I found the valve for the pressure vessel, (just like car tyre valve) but when I pressed on it there was high air pressure but no sign of any water.

Your pressure vessel has a membrane running through the middle of it. Air on one side and water on the other.
With no water in the vessel I would charge the air side up to 1 bar / 14.5 PSI through the schrader [car tyre] valve.
To achieve the 'no water in the vessel' status you need to let some water out of the system and keep letting it out as the air side fills up. Most of us cheat and use the PRV but officially I have to tell you to use the drain off valve if fitted which is usually difficult to get to and located at the lower right hand side of the boiler.

As water is a liquid it will not compress as a gas [air] does; therefore it must be removed to allow maximum use of the vessels space.

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RAVENHEAT CSI 85 COMBI BOILER, PRESSURE KEEPS DROPPING?

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