Leaking cold water outlet is the Wood burner the issue?

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Swashbuckler75

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Hi there,

I hope someone can help as I'm struggling to diagnose what the issue could be and not having much luck getting a professional tradesperson to look at the problem

I moved into a property last year with a wet system installed where the wood burner can be used to heat the hot water and underfloor heating. Mainly we use the regular combi boiler for day to day hot water

There is cold water pipe at the back of the burner that exits out into the garden. This outlet pipe has been constantly running for months. I got a plumber to have a look to and eliminate any other causes but thinks it is to do with the wood burner.

I've found that when I turn the safety valve at the back of the burner to flush cold water through a greater volume exits out and then as the safety valve locks back into position the water subsides to the constant dribble as before.

I tried turning the safety valve on for about 30 / 45 seconds and the expansion tank made a really loud groaning noise as it was filling up with water. I don't know if that is related or not.

I think the issue is with the wood burner but I could be wrong. I'm hoping someone might be able to point me in the right direction.
 
It may just be the ball valve on the expansion tank is a bit old, or its a low pressure valve on a high pressure supply, pics of the various devices (tanks, valves, LLH or buffer tank) would be helpful
Good odds yon safety valve has got old and tired- it is probably a pressure and temperature sensitive device, it is designed so if parameters are exceeded it opens and allows scalding and/or high pressure water out (to be replaced, hopefully, by cold water from the header tank). They don't last forever, especially if someone has been using it as a lazy drain point.
 
oldbutnotdead said:
It may just be the ball valve on the expansion tank is a bit old, or its a low pressure valve on a high pressure supply, pics of the various devices (tanks, valves, LLH or buffer tank) would be helpful
Good odds yon safety valve has got old and tired- it is probably a pressure and temperature sensitive device, it is designed so if parameters are exceeded it opens and allows scalding and/or high pressure water out (to be replaced, hopefully, by cold water from the header tank). They don't last forever, especially if someone has been using it as a lazy drain point.
Click to expand...

Thanks. I've put a link to the images of the valve at the back of the wood burner, the ball valve and the outside water leak. Hopefully the photos might help - Here's a link to the photos
 
In future it's much better to just drop images into your post rather than sending people off on another app hunt....
Good to see a metal F & E tank, good odds the groaning noise was the ballcock dragging down the side of the tank.
The valve pic- assuming the feed from the woodburner comes into the bottom of it & the overflow pipe goes out the side then yes it's a temperature/pressure vent, seals will be worn, replace- 2 bar 95 degrees is the usual, Screwfix sell them.
How does the combi connect to the woodburner- there should be a neutral point somewhere if combi and woodburner can both heat the UFH and DHW cylinder
When you refill after draining down (which you'll have to do to replace the valve) put some inhibitor in- system will be on fresh water at the mo, not good for long life
 
Thanks @oldbutnotdead . It sounds like from what you are saying that it's most likely the valve that needs replacing. Here's a question - is this a job for a plumber or heating engineer or can I do it myself? Because the system came with the house and the previous owner 'forgot' who installed the woodturner, trying to get a professional to look at it is like finding a hen with teeth. Tried a few HETAS engineers in the South East and they won't service a system they haven't installed, which doesn't help my situation.

You mentioned a neutral point, I'll have a look but what should I be looking for? Is it a valve of some kind and where would I likely to find it? The way the system's been installed I've got the wood burner in my main living room, the combo boiler in my utility room, and my hot water tank and expansion tank upstairs.

My old house had a regular combo boiler and storage tank in the loft and it was pretty straightforward system to diagnose any problems, but this wet system is a ball of confusion for me
 
Your description seems to be very confused. You say you have a combi boiler, but also an expansion tank in the loft, which is very unusual, and a hot water tank (cylinder?) which is also very unusual with a combi boiler. Similarly you say your old house had a combi boiler with a storage tank in the loft. To come across one combi with a loft tank in your lifetime as a homeowner would be extremely unusual, to come across two is almost lottery odds. I suspect you don't have what you think you have. Could you post photos of the boiler, cylinder cupboard, and woodburner? Wide enough shots to be able to see the general installation of each. If you have the make and model of your boiler that would help too.
 
As @muggles , a bit more detail needed.
It's not clear whether the 2 systems are linked. You say the woodburner can heat the UFH and DHW cylinder, can the gas boiler also heat the UFH and DHW cylinder.
NB not all gas boilers are combis. A combi boiler can instantly heat cold mains tap water to hot, no cylinders required. You may have a system or heat only boiler, or an unusually plumbed combi.
HETAS- hmm. Pics please as @muggles
 
Hello @oldbutnotdead and @muggles

Ok, I've attached some photos of my system. I have a greenstar condensing boiler not a combo boiler as I previously said.

I've also took a photo of the water tank (unless it isn't a water tank) and the expansion tank above it.

I may have led you down the path on whether the wood burner heats the hot water and underfloor heating as we have only lit the burner a handful of times last winter and so the greenstar boiler is doing the hotter and UFH . There are a couple of pipes running at the back of the burner so I guess it can heat the hot water. The model is Koppe Caron Aqua - here's the spec sheet for it



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Looks like quite a decent setup there. The big green thing is your buffer- basically a big hot water cylinder. The black thing on the floor to the left of it looks like a loading valve (prevents condensation in the woodburner when it is firing and prevents backflow from the buffer when burner is cold & buffer is hot).
I can't tell from looking at it whether your woodburner is heating the cylinder directly (ie the cylinder water circulates through the woodburner-preferred option imho) or indirectly. Likewise don't know whether the Greenstar is direct or indirect.
Your hot water flow and pressure should be excellent- the black lump on the right of the buffer looks like a plate heat exchanger- can deliver up to 30litres/min of hot water at mains pressure. The heating (UFH, other radiators) may also be connected to the buffer so the woodburner or gas boiler can heat the buffer & the buffer then heats the house (same setup as I've got).
Have a good look at the buffer tank and all the control systems, see if there is an installers label on it. If you can find the serial number of the woodburner, get onto the suppliers & see if they have a record of a company buying it, ditto with the loading valve and gas boiler.
Changing that pressure relief valve can be a DIY job but it's a big and quite complex system, if you can get either the installer or another HETAS bid or a good heating engineer (not a boiler slinger) to visit (yes you'll have to pay them) and investigate what is connected to what and how.
If system was installed professionally it will be impossible to isolate the woodburner from the buffer and header tanks (to avoid turning it into a steam-driven bomb) but it would be wise to get someone to check before you start draining down....
 
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