A classic with a twist - no HW, CH OK, conventional boiler

I'll give it another go, thanks.
It was higher; until the problem began last week - we had a new upright rad put in as part of the bathroom, and the top of that rad is now higher than the top of the HW cylinder.
 
The water looks clear.

Well, after fully opening that gate valve and bleeding as advised (only bled it to the dribble, didn't do a second bleed until it spurted) it appears that we have hot water again.

I'm not convinced it's fully sorted (because i am a pessimist) but I haven't had the immersion on since yesterday and there's proper hot stuff coming from the taps, which can only be a good thing.

Tomorrow morning is the big test: if I wake up to hot water I owe some of you a drink!!

Would it have been air in the coil that the bleeding solved? If not, what/where? I'll be asked tomorrow I'm sure by the bathroom fitters who took me for a naiive woman who didn't understand plumbing (or indeed, how to use the internet......)

Should I close the gate valve which leads to the bleed point on the pipe coming out of the tank? What purpose does it serve to leave it open or closed?

This whole system is riddled with air, we constantly have to bleed the rads and its as noisy as hell. I might start a whole new thread on the woes of it, including not being able to turn the boiler up past 2 (of 6 I think) because it kettles and trips the boiler out. I can't afford to replace it at the moment, but after this I'm seriously considering getting a loan and doing so.
 
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have a look at the little tank in the loft (the feed and expansion tank). Is it warm? does water run into it when the pump starts up? Is there thick brown mud at the bottom?

As for the kettling, you can do a simple DIY chemical clean for about £30 in materials. It will not be as good as a pro clean, but may do some good, and the chemicals are not aggressive so unlikely to do any harm. You just need to access the drain cock and the f&e tank.

Quite often people leave the empty chemical bottle in the loft so you can see what was used. They ought to put a label on the boiler or by the cylinder with the date, too.
 
I looked in that tank earlier. The water is a bit brown but not mega-muddy, if there's a scale of such a thing. It's brown around the sides of the F&E tank.

The water that comes out of the rads is clear, when I bleed them, and the water that dribbled out of the bleed valve earlier was clear too. Where would the brown stuff go?

I'll look into a clean, there is actually a bottle up in the loft seo that'll help. Previous owners didn't care a jot about this house so I doubt they did much other than to pay someone a lot of money to cock it up do it.
 
you will not be aware of the mud unless you stir it up (not recommended, unless you are baling it out at the beginning of the cleaning cycle). The sludge tends to settle into the bottom of the radiators and in the boiler, so again you will not see it unless disturbed. The cleaning chemical dislodges it so it is carried away in the moving water so you can drain it out.
 
Kettling boiler is often a sign of sludge in the system, a chemical clean will no absolutely no harm, and may even give you noticeable improvements!. It can take a long time, if ever to pay back any savings on gas over the installation cost of a new boiler, and the system would have to be cleaned prior to fitting a new boiler to it anyway. The 'air' people think they are releasing on a badly sludged system is in fact, hydrogen, a product of the corrosion happening inside the system. :cry:

I dont think it would take a lot of air in that coil to stop circulation, although you dont say how long it took for water to appear? You've released any trapped air and its now working so seems to prove a point!

If its working, dont touch it! I'm unsure of the purpose of that gate valve, but closing it would shut off the circulation through the cylinder, and lead to no hot water again..... Edit. It may be there to restrict flow through the coil, for colder months when heating is also on, the water will take the path of least resistance, and so the cylinder will get the lions share until stat is satisfied and closes motorised valve to HW, thus forcing all the flow to CH. If this valve is left half closed it will help restrict flow to HW ensuring CH works effectively when both are required.
 
Well, it looks like I owe some of you a drink. The immersion is off and has been for over 24h, to prove a point it's off in the fuse box!
Hot water all present and correct this morning.
However: a pump is supposed to be going onto the system today and I fear another drain down is needed... I know what to try first if it happens again.

I'll certainly look into the cleaner, probably in slightly warmer months in case something else breaks. I'll do anything to try and improve the running / efficiency of the system. However, we do have a Magnaclean on the system, it's OK to use stuff with that, yes? That isn't very dirty at all either.

Point noted about a new boiler: I'm nervous of this system because I don't believe it was looked after before we moved in, and the plan with the house was, eventually, to replace it. (It's 20yrs old) I wish I'd persuaded the family to pay for that over a bathroom refit!

Thank you so much for all your help on this one. I'm off to close the gate valve to halfway.

(The air took a few minutes to escape from the bleed va!ve, but it was escaping very, very slowly)
 
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If you are using a cleaner such as X400, it should be done during the heating season, a it should be circulated through the radiators for a few weeks before draining. After about 4 weeks the sediment starts to settle again.

It's possible yours was cleaned before the Magnaclean was fitted, which would have been sensible, but why is it still gassing?

Is the f&e warm, and does it run when the pump starts?
 
The gate valve is a balancing valve to balance the heat flow between the CH and the HW.

It is not very critical.

The best way to set it is so that you have a differential of 11 C between the flow and return with both CH and HW on together. That is the temperature with a non condensing boiler like yours. Or hand measured, flow hot and the return a little less hot.

But for the time being close it and open about 1 1/2 turns.

Tony Glazier
 
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Sorry for delayed reply. The pump that went in was a booster pump for the shower (my Grundfos pump remains intact), and HW has behaved since I bled the valve. Will close/open the gate valve tonight when home, thanks for the advice.

Will look into the x400 towards the end of Feb and will let it do it's thing for the time needed.

The heating was balanced at the weekend - it transpired that three new rads have been added (2 before we moved in) and have never been balanced. Since that, it's been running quieter, less kettling.

The F&E had a leak on the overflow which I sorted, removed the pipe and siliconed around it before refitting. The F&E tank was cold. I adjusted the ball valve slightly so it put less water in as it was a bit high (close to overflow). Without being in the loft when the heating comes on (I haven't done that yet) I can't tell if it runs on startup. However, the levels have changed since I have been in and out of the loft so it must be doing something.

I remain unable to turn my boiler up to 3 or beyond, I moved it to three and the boiler tripped last night, without kettling this time though.

This poor old 20yr system really is limping along I fear...
 
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What do you mean by 'Tripped'? Old fiddles play the best tunes, with a bit of TLC you will probably get a few more years out of it. Normally, if the system design is up to modern(ish) standards, a powerflush is all that is done before fitting a new boiler onto the old system. If your Potterton is still going, leave it where it is!
 
Tripped... I don't know how to explain it. Basically there seems to be air in the pipes, it clanks a bit, often when the system is kettling, and then the boiler pilot light goes out and I have to press the reset button underneath it. I didn't know what else to call it; resets itself? Dies?!!

I'm hoping to be nice to it and try and limp it on for a year or so to let me save up something towards it. It was installed in 1995 I believe.
 
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