Bockage in system - boiler pumping over/pump banging

[alastairpearce]

Hello,

I have posted a separate thread on here about an ongoing problem, however I have now diagnosed what could be a blockage I hadn't found before, and think this warrants a new thread.

A brief summary of my previous issues. Boiler pumping over into feed/expansion tank, with rumbling and steam bellowing into tank. Subsequently causing grinding noise in pump.

Previous solutions explored - just had my system power flushed to remove blockages, which I thought was successful. Also, new Grundfos selectric pump installed, so the pump is not at fault.

Checked cold feed with a magnet and no blockages in cold feed.

Boiler thermostat working fine (boiler fires when turned up/turns off when stat turned down).

Now I am investigating the Danfoss Ravi thermostatic cylinder valve, and have discovered that what I believe to be the bypass pipe is blocked where it enters the thermostatic valve. I have attached a circled in red where the blockage has been identified.

My questions are as follows:

1. Is this pipe indeed the cylinder bypass?

2. Could a blockage of this nature cause pumping over/steam into the feed/expansion tank?

3. Is there any way of removing this blockage without draining down the system? I have literally just had my system power flushed and don't want to lose all the chemicals that have just been put in the system, which I have paid for.

I appreciate all the help on this forum, thanks very much for your time.

Alastair Pearce

 

[WHPES]

From your picture it looks like your system is a right old-fashioned affair. Do you have a photo showing more of the system in the photo above?

My advice would be to update the system with modern controls ("S Plan")

 

[alastairpearce]

It is quite an old system, but up until recently has been running sweet as a nut.

There is another photo in this thread I posted previously.

http://www.ukplumbersforums.co.uk/c...coming-out-vent-pipe-into-expansion-tank.html

Do you know how a blockage could be removed without draining the system, or without forking out £100's on a costly repair?

I don't have a lot of money to chuck at this system, so the most cost effective repair would be best for me, which I believe would be removing the blockage.

With a power flush (which I have already had) I don't believe further blockages will be a problem after this one for some time.

 

[WHPES]

If I came across this set up at a customer's house I wouldn't even try to fathom it out but would go straight for upgrade to S plan and conversion to sealed system. The reason being I could spend several hours trying to find a fault and in that time could have done the modification. Your system doesn't look like its been installed properly anyway. Could be the thermostatic cylinder valve but I'm not even sure if you can still buy them.

Whatever you do you cannot investigate without draining the system anyway

 

[SimonG]

If I came across this set up at a customer's house I wouldn't even try to fathom it out but would go straight for upgrade to S plan and conversion to sealed system. The reason being I could spend several hours trying to find a fault and in that time could have done the modification. Your system doesn't look like its been installed properly anyway. Could be the thermostatic cylinder valve but I'm not even sure if you can still buy them.

Whatever you do you cannot investigate without draining the system anyway

Unfortunately you still can get thermostatic cylinder valves, not a fan.

But agree totally with your comments re S plan.

 

[alastairpearce]

Okay, so how much would you expect to be charged for upgrading to an S Plan?

(ball park figure, not an exact quote)

 

[WHPES]

depends on how much alteration there is to do. Stab in the dark at £600 for S plan and sealed system based on my last conversion but one would have to inspect it properly. Could be much more or possibly less than that.

Bear in mind a properly controlled system will save you a couple of hundred a year in running costs.

 

[alastairpearce]

Okay thanks.

And what would you say is the likelihood that the thermostatic valve is to blame?

I mean, £600 give or take is a bit of a gamble if it's not even solving the problem.

What does an 'S-plan' system do, and why would it be more reliable that what I've got now shown in the photo?

I apologise for the questions, but I know very little about plumbing.

 

[SimonG]

The thermostatic valve is about £200 on its own!

 

[alastairpearce]

Yeah i saw that, everything is so expensive!

So how does the S-plan work differently to the thermostatic valve? It sounds like a good solution, but I don't know the difference.

 

[WHPES]

Central Heating Controls and Zoning - DIYWiki

The S plan is superior to the Y plan and if you are doing a revamp its the way to go.

 

[SafeGasInstall]

I would suggest S plan along with new programmer and TRV /boiler/cylinder
round my way I charge 4k for full upgrade to efficient system ! But is not waisted £ as is home improvement adds value to the house and is reliable and efficient system ,having the money to do it this is the hardest thing in this days

 

[bengasman]

Bypass is effectively an emergency outlet, and therefore unlikely to be the only problem. Bound to be a blockage somewhere.
That is presuming the system is installed correctly.