Backflow prevention valve question

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Backflow prevention valve question

Post  jgmr on Wed Dec 07, 2011 3:11 pm

Hi All,

Quick (hopefully) question about my Electramate boiler:

Recently the CA Backflow Prevention Valve has started leaking and making a hissing noise. It's got to the point now where the leaking is a constant drip / trickle and is often missing the overflow pipe and causing a small puddle on the floor. It seems that this is a fairly common issue with the Electramate over time (mine is about 7 years old) where the valve gets blocked and simply needs replacing.

So, my questions are:

1 - does the above sound correct and I just need have the valve replaced?

2 - when replacing the valve, is turning off the water inlet sufficient or is a drain of the system needed?

Thanks in advance to anyone who reads this or gets back to me.

Cheers,

JGMR

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Re: Backflow prevention valve question

Post  mike on Thu Dec 08, 2011 1:29 pm

What EM is it?
Mike
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Re: Backflow prevention valve question

Post  jgmr on Thu Dec 08, 2011 3:28 pm

Hi Mike,

Electramate 2000, model 9E260

JGMR

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Re: Backflow prevention valve question

Post  jgmr on Sat Mar 10, 2012 6:06 am

Hi - wondered if anyone had any thoughts on this?

It seems to have gotten a lot worse recently and the puddle is getting bigger! I think it's just a case of replacing the valve (have found one available online) but would like to see if anyone can confirm this before I go ahead.

Thanks in advance,

- JGMR

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Re: Backflow prevention valve question

Post  Midland Boilercare on Mon Mar 12, 2012 1:54 am

Hi

You are quite right, the CA valve does require replacing. The unit will also require draining to replace it as one side is connected to the mains cold water, however the other side is connected to the heating system.
Depending on which configuration of the unit you have, some require a full drain off, but on some can you can get away with a partial drain off.
Don't be tempted to just open the nuts and try to "snatch" the new one into place. All of my engineers are instructed to drain the units at all times for this type of repair. Be aware, if the unit is functioning correctly, you could have water at upto 70deg C in the unit, and that would leave you with a serious burn!
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Re: Backflow prevention valve question

Post  jgmr on Mon Mar 12, 2012 12:55 pm

Hi David,

Many thanks for the response. I have a friend of a friend who does some boiler work but is no Gledhill expert so I'll ask him to pop over and help me drain the system and fit a new valve (found a couple of places on the net which stock them).

I'll let you know how the work goes!

- JGMR

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Re: Backflow prevention valve question

Post  jgmr on Wed Apr 18, 2012 5:31 am

Hello - quick update on this one and (unfortunately) another problem!!!

Drained the system last weekend and swapped out the CA valve nice and easily. Turned the cold water inlet back on but the system was refusing to fill / commission for some reason and pressure was at 0.

Tried to adjust the pressure relief valve to see if this made a difference but no change. Called up my usual Gledhill engineer who talked me through a known issue with the Pressure Relief Valve not 'kicking in'. Basically I needed to press in the small brass screw (with a thin flathead screwdriver) which is used to change the pressure. As soon as I did this the whole system kicked into life and started to fill up. Pressure was up to just below 1 bar in a short time.

Unfortunately, after a couple of weeks of good service, the Hot Water in the house was not working yesterday. When I checked the boiler, pressure in the system had again dropped to 0. I used the trick above and as soon as I pressed in the brass screw, it all kicked into life again and pressure immediately shot up to 0.8 bar.

This worked fine for another day (with use of heating and hot water / showers) but again the pressure dropped this morning and required another poke. This morning though, i noticed that the pressure has started dropping down FAST when the hot water is used.

In summary it seems that the Pressure Relief Valve is now not doing what it should be and needs constant attention to keep the system working. Is there a known fix for this or will it be a case of having the Valve replaced?

Thanks again for reading and appreciate any answers / advice!

- JGMR



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Re: Backflow prevention valve question

Post  Midland Boilercare on Wed Apr 18, 2012 6:44 am

Hi again

There are actually two problems here.
1] The sticking pressure limiting valve looks like it may need replacing if it is sticking continually
2] Pressure that keeps droping indicates that you are loosing water somewhere, and this is the most important problem of the two that needs attention.

If you drained the unit using the expansion relief valve (the red safety valve adjacent to the bottom pump) then there is a chance that this has become dirty and will require cleaning or replacing. Start by checking this.
Secondly, check the auto air vant and ati-vacuum valves on the top right hand side of the unit.
Finally check the radiator valves for signs of water leakage.

Whn you have stopped the leak, you will have stopped the pressure falling, and by default, the pressure limiting valve won't have to operate in the first place. Simples!!
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Re: Backflow prevention valve question

Post  jgmr on Wed Apr 18, 2012 10:05 am

Hi again David,

Just to confirm, the system only seems to lose pressure when the DHW is being used (unsure about heating as of yet but can check later on). If I leave the boiler switched on and simply don't use any Hot Water, then pressure stays just where it should be below the 1 bar line.

Did a fairly thorough check for leaks this morning and everything seems ok.

The system was drained via the main Drain Valve on the bottom of the appliance so didn't touch the Expansion Relief Valve - but will give that a check later on also. AAV / AVV both seem OK too.

My gut feel is simply that the unit isn't refilling when Hot Water is used - potentially down to a problem with the Pressure Valve sticking.

It's sounding like another swap-out! At least this one is the better side of £50!!

Thanks again and all advice much appreciated!

- JGMR


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Re: Backflow prevention valve question

Post  jgmr on Sat Apr 21, 2012 2:33 pm

Quick update...

since the last post everything has been just fine. had the heating on for a few hours to check, showers and HW every day, and pressure has stayed around the 1bar mark.

I'm probably going to just leave it for now and see if the pressure drops again and, if so, I'll give the Gledhill guy a shout.

Many thanks for all the advice to date - this place is an invaluable resource!

Cheers,

- JGMR

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