New central heating boiler

[Witzend]

In July, we finally got rid of a Baxi condensing boiler to replace with new Glowworm Micron 70FF plus new rads. The system was flushed with Fernox and has been refilled about 5 times. We had problems at first with all the rads getting red hot upstairs and not down...plumber changed a bit of pipework, then no hot water at all...hep pipe to cylinder kinked...plumber changed it. We've had three pumps since July, this one being a heavy duty. There are valves fitted at the flow-pipe and return pipe at the boiler and one fitted next to the cylinder. We've had banging in the boiler, which we were told was air (didn't shut down the boiler tho) but by the beginning of the week this had gone and the boiler has shut itself off every morning this week.
Yesterday in this long saga we had two rads which were not getting warm,flushed through and the valves checked. The plumber closed down the bypass pipe a bit to stop the hot water rushing up into the overflow tank in the loft. He also got rid of some air.Everything nice and cosy yesterday evening but the boiler shut itself down once or twice. The boiler had to be rest this morning but only took one attempt unlike the rest of the week when we had to nurse it. Rads soon warmed up - but this evening upstairs was red hot, downstairs rads cool or just barely hot at the top (room stat set to max, boiler on halfway btwn min and max- or it shuts off) and the pipe to the central heating refill tank was hot again.

I'm thoroughly fed up of it. Any ideas or is the nearly 3 grand spent been a waste of time?

 

[Witzend]

sorry "boiler had to be reset this morning not rest!

 

[kevplumb]

closing the bypass wont stop pumping over and closing it down sounds worse i would think your system by pass needs setting properley and the system needs balancing

 

[Witzend]

And so quick too Kev!

Any other ideas would be appreciated. I hate being cold!

The system was supposedly balanced yesterday.
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[kevplumb]

supposedly (says it all)

 

[Witzend]

 

[kevplumb]

so i assume you (or your installer ) knows how to balance a system and what the bypass is for ?

 

[Witzend]

I'm beginning to wonder what they really know! That's why I've called here, so that I can suggest something else for them to try...
I've also decided to email hep-heat.co.uk and will post their reply if i get one!

 

[Witzend]

Boiler had locked out this morning and after it had been reset (3 or 4 times) the pipe for refilling the CH was warm in the airing cupboard and also the same pipe under the floor next to the boiler. Any ideas?

 

[Witzend]

And I did get a reply first thing this morning. Here it is.
Thank you for your email. The failed pumps, noise and erratic heating up of radiators all point to major system problems - not a boiler problem. The
most likely cause of the boiler locking out is that it is overheating
(hence the banging). The pumping over at the expansion tank indicates a
possible fault in the configuration of the system or that the pump is set
too high. The system is also needs balancing so that the radiators all
heat up at the same rate.
It may be prudent to obtain guidance from another local installer.

Any ideas what we can do?

 

[DP]

Boiler had locked out this morning and after it had been reset (3 or 4 times) the pipe for refilling the CH was warm in the airing cupboard and also the same pipe under the floor next to the boiler. Any ideas?

You also mentioned you have an overflow tank

A system should either have a header cistern or is sealed system with an expansion vessel which is charged up to working pressure with a filling loop disconneceted once the system has been charged to (in my case 1.5 bar- others do it to 1 or 1.25 bar)

I will probably be shot down in flames, but I have to date cleared half a dozen systems that had a peculiar type of blockage created by plastic pipe. Not found same in coppered installations. Mainly do boiler repairs, servicing and breakdowns.

 

[ChrisR]

DP it's vented as it is - are you suggesting it should/could be sealed/pressurised to solve the problem? That would certainly solve what Hep have correctly identified as faulty system layout.

Witzy - look at the boiler Manufacturer's Instructions to see if it says the boiler can be used on a "vented" or "open" system, which you have. Some can, but more are saying that unvented (sealed) systems should be used.

You should never get any pumping-over into the header tank, regardless of the pump setting. Maybe your plumber has left a dodgy configuration in place. How much of the pipework has he changed?

Using plastic per se wouldn't introduce the problems you have now, though there are systems where long-term problems do bring its presence under suspicion.

There are various ways to get "air" into a system, but I think the most likely in your case is in the water which is going up into the header tank, and getting aerated, then being draw down into the system. If the air can't easily get out it can collect in the boiler and give the problems you have. It has to be able to get out, up the vent pipe, easily. The fact that this isn't happening in your system points, again, to incorrect configuration of the feed and vent pipes, and the boiler and pump, relative positions.

The flow from the boiler should come out (from the correct pipe!) then rise to the junction where the vent pipe goes up and over the feed tank. Next is the junction where the feed pipe comes down. (These two junctions can be combined in a can thing called an air separator, which might be a simple solution in your case). Next on the circuit should come the pump, then the motorised valve(s) , and on into the rads/cylinder. Just about any other configuration is likely to give problems of one sort or another.

 

[Witzend]

The heating actually came on by itself this morning and stayed on . All rads were hot but we have a whooshing sound coming from the boiler, like water rising up on air.

 

[Witzend]

The return from the cylinder and the CH expansion feed pipe is on the return pipe to the boiler LHS (under floor). The pump is after the bypass pipe on the RHS flow side of the boiler (under floor).Is this wrong?

 

[Witzend]

Still get loads of whooshing air sound in boiler. Lots of air collecting in one upstairs rad (strangely in the middle of the run) and the expansion tank feed occassionally gets quite warm.

And because I'd turned up the boiler setting to halfway yesterday it soon shut off again this morning