Please Help. Overflowing F&E and brown tap water.

[jonjay3012]

Hi, having a bit of a disaster at the minute. Just from installing a new kitchen every little job seems to be going wrong. The latest is the heating system.

During the kitchen change we decided to take the old rad out, and as doing that decided to change 2 other old rads that had been leaking at the same time. Yesterday I drained the system down (although it didn't drain well so ended up using bungs), and took off the 3 rads. We don't have the replacements yet so the pipes are just capped off with stop ends.

We live in an upstairs maisonette. We have an old back boiler and open vented gravity system There is a large cold tank in the loft and a small F&E tank which is higher than the cold. The hot water cylinder has an emersion but we use the boiler to heat water.

When I got in today I noticed the water in the loo was brown. Ran the bathroom cold taps and sure enough, brown water. Kitchen tap and shower are clear, but assume that's because they are direct to mains supply.

A bit of investigating in the loft and the F&E tank is full with hot water and is draining down the overflow, which seems to go back to the main cold tank. Not sure if this is standard but seems a bad idea as our cold tank is now contaminated with brown water from the F&E (with heating system cleaner that I added when refilling the system yesterday as there is definitely some slugging in there judging by the crap that was at the bottom of the F&E).

Bit of closer looking and the reason the F&E is overflowing is that the vent pipe (the one that loops over the top) has a slow flow of hot water coming back in to the tank.

I really have no idea what to do and any help would be really appreciated. I'm worried as the water level gets really close to the top of the F&E tank, but hopefully the overflow can keep pace with the filling. I've turned off the heating as this stops the vent pipe from leaking water back, but the wife will moan in the morning when it's blooming freezing, and I can't just leave the heating off indefinitely

Normally I'd get the plumber out but, just my luck, our usual plumber is on holiday and when it comes to trades I like to use people I know and trust.

Thanks for any pointers and help.[/b]

 

[Agile]

It sounds as if you have a plumbing disaster area!

Your leaking rads were perhaps following the pumping over problem?

That brings new oxygen into the water which rusts the rads from the inside!

There are several cures but most need an examination of the system and choice of possibilities.

Tony

 

[jonjay3012]

Thanks for the quick reply


There was definitely rads rusting from inside, but not sure it's necessarily resulted from the pumping over. The only reason I say this is that we have never had an issue with brown tap water before, and we definitely would have done if the F&E had been overflowing in to the cold tank like it is now as the water drained from the system yesterday was far from clean.

Also the old rads may have been on for a very long time. We've been here 5 years and they were here when we moved in.

I know we will have to get someone out for a proper look for underlying problems but is there anything that could have caused this pumping over issue from my draining the system down and taking off rads yesterday?

Cheers

 

[Agile]

Pumping over does not have to be accompanied by over flowing!

Tony

 

[DP]

OP unlikely to be pumping over as feed/ expansion and vent pipes are off the cylinder which is gravity circulation loop.

Vent the radiators as chemicals likely gassing, depressing water in the rads which is pushed up into the header tank. Overflow hence into the CWS.

Easy cure is reroute the overflow and tee it into CWS overflow which should then discharge to external, not into CWS

 

[jonjay3012]

Well, last night before going to bed I manually emptied a bucket and a half of water from the F&E tank to drop the level well below the overflow and to the point where the ball valve shuts off, just to stop water getting in to the cold tank.

This morning after seeing DP's advice, I bled off the 3 remaining rads that are connected to the system, after having the heating running for a bit and then turning off again. There was a little air in the living room, and a bit more in the bed and bathrooms, but not a huge amount in any. Before bleeding the rads, while the heating was on, the vent was still discharging in to the F&E but I couldn't tell if the water level had risen significantly as the heating hadn't been on for long.

When I get in tonight I'll fire up the heating again and see what happens.

The thing that is confusing me though is, if the ball valve is functioning correctly, how can more water get in to the heating system. Surely when the ball valve in the F&E shuts off any water in there should just circulate and therefore even if discharging from the vent pipe should remain at a more or less steady level?

 

[DP]

Water could enter the heating side if the hot water coil is perforated, be it a pin hole. Next thing you could try is isolate the cold supply to cylinder that shuts off the hot water to the hot taps.

 

[jonjay3012]

Water could enter the heating side if the hot water coil is perforated, be it a pin hole. Next thing you could try is isolate the cold supply to cylinder that shuts off the hot water to the hot taps.

If this was an issue, would we not have noticed discolouration to the hot water before? At the moment there is no discolouration to the hot water, only the cold, but I'm assuming that this is because the hot tank is still virtually full as it hasn't been used since the F&E started overflowing.

 

[Agile]

Bit of closer looking and the reason the F&E is overflowing is that the vent pipe (the one that loops over the top) has a slow flow of hot water coming back in to the tank.

DP, he has already confirmed that it has been pumping over!

Exactly why we don't know because with a correctly configured system on gravity hot water that would not usually occur.

But it needs investigating urgently before the rest of the rads start leaking!

Tony

 

[DP]

Well in that case the gravity HW must be converted to pumped without altering the feed and vent pipes

 

[jonjay3012]

Well we've had the plumber round and he's adjusted the pump speed which has stopped the vent pipe discharging water. He is pretty sure the problem with the F&E overfilling is a blockage in the system. apparantly the return from the hot water cylinder is not bringing even luke warm water back and the pipe temperature isn't changing at all.

Looks like a flush is the only realistic option.

Think it's about time we looked at updating the system, plumber was pretty shocked by the pipework, doesn't seem like the most thorough or planned job when it was fitted in the first place.. Might get the whole lot ripped out and get a combo fitted.

 

[buck51]

just to clear something up you did say the bathroom cold taps and the toilet were filling with brown water

I think you will find this is because they are fed from the cold water storage tank in the loft

if you turn your main cold water off you will find that these taps still run till the tank is empty

so it would be a good idea to replumb these off the cold mains,

so you are not brushing your teeth and whatever with stored tank water.

 

[buck51]

also do you have a mixer tap or shower any where in your property.

 

[DP]

Jonjay, Does the pump run during HW demand?

The tee at the cylinder does block up. Get your plumber to locate and fix. Magnet will come in handy. Also, turning down the pump speed is not a fix- a fix would not need pump speed reduction to stop pump over. Pumpover is due to incorrect plumbing.

 

[jonjay3012]

@Buck. I know that the bathroom taps and toilet are fed from the cold water tank (although I didn't before this happened). Replumbing might be an option but not a priotity at the minute.

We have a mixer tap in the kitchen and on the bathroom sink. I've also got a mixer to go on the bath, but not put on yet. The shower is electric and mains fed.

@DP, I'm not sure whether the pump runs on h/w demand to be honest, but can check later when I get in. I'm not sure there is a T at the hot water cylinder from memory. A pipe in and a pipe out, running up in to loft to the main web of pipes above the boiler/below the F&E.

I know that turning the pump down isn't a fix and my plumber didn't claim it to be. Just a temp measure until we decide what we're going to do, which stops the pumping over and overfill of the F&E. As we've got only 3 rads going at the moment the pump isn't having a hell of a lot of work to do. Plumber also agreed that the plumbing in there is a bit of a mess and said that if we decide to go with a new boiler he'd strip the lot out and put fresh pipes in, properly.