Radiators aired, boiler locks down every 10mins


Postby Othello » Thu Jan 10, 2008 4:28 pm

I have a new Glowworm Ultracom 18sxi boiler in a Y-plan. The system works fine from cold but once hot any interruption such as end of hot water timed segment or advancing the heating for another hour when at the end of its segment leads to boiler locking down. After this the boiler lights approx every 10mins, overshoots target temp (60C) and locks down, pump continues to run. This can go on for an hour or more while the system cools down and the radiator temp is at best aired. Eventually when the system is cool enough the boiler will stay in and the radiators all get hot again. The room stat is turned up to 30C to make sure it isn't affecting anything. I've checked the room temp where the stat is and it is only about 17C. Could the problem be due to a restriction in the system somewhere, preventing the hot water getting away from the boiler quickly enough?
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Postby htg engineer » Fri Jan 11, 2008 3:27 pm

"This can go on for an hour or more while the system cools down and the radiator temp is at best aired"

aired ?

have you checked the pump is running properly ? turned pump speed up and vented pump ?

Could be a faulty thermostat, sticking.
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Postby Othello » Fri Jan 11, 2008 4:38 pm

Thanks for the suggestions. The pump is set on the faster speed but I have tried both speeds on the pump (which is built into the boiler) but it does not seem to make any difference to the problem. The tone of the pump increases on the faster speed as you would expect. I haven't vented the pump so will have to give that a try. I've checked the room stat and it clicks off at about 17-18C which is what I've measured the room temp at.

Many thanks for the advice.
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Postby rosebery » Sun Jan 13, 2008 6:22 pm

I stopped reading after "I have a new......"

That implies it hasn't been fitted that long so your best course of action is to get the installer back and tell him to fix it!
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Postby Othello » Mon Jan 14, 2008 8:20 am

I have spoken to the plumber who hasn't got a clue and thinks it is probably the boiler. I had glowworm engineer out to it and they say it is the system that is at fault and not the boiler. I am beginning to think that the plumber should have recommended a powerflush for the system before he put the new boiler in. When I asked him about a powerflush he said it was unnecessary, but the system has been in at least 15years.
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Postby rosebery » Mon Jan 14, 2008 9:32 am

IMO it's the responsibility of the installer of the boiler to make certain that the system is functioning after he has finished. It clearly isn't. It seems to have worked OK with the old boiler but not the new. So what's changed? - the boiler!

Did Gloworm install it themselves or was it a 3rd party installer?

If the former their engineer hasn't got much of a leg to stand on pointing in the opposite direction. If the latter then he has probably. It's the installer (whoever that was) you need to get back in. Don't forget under EU legislation he has a responsibility for latent defects for 6 years if he was paid to do the job.

As regards flushing the system that should have been done as a matter of course by the installer (although not necessarily a powerflush) after he had completed his pipework to get rid of any debris, solder, flux etc before commissioning the system. Did he?

Cheers
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Postby rosebery » Mon Jan 14, 2008 9:33 am

BTW what does "........the radiator temp is at best aired." mean out of interest.

Cheers
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Postby Othello » Tue Jan 15, 2008 2:03 pm

Thanks for your advice.

The boiler was fitted into a new extension by a local plumber along with 2 extra radiators. He insisted we needed a system boiler as he was not happy with the previous setup which he termed prehistoric and created a Y-plan, with a 3-way valve, room stat and cylinder stat. He did add a system cleanser when the boiler was first installed and then a few weeks later when the radiators were added he drained the system down and added a system protector.

My thoughts are that the system is too restrictive for the boiler (although the boiler itself is not reporting any faults). Whether this is due to debris or an air-lock I don't know. I say this because when I try to even out the radiator temperature to get more heat to the downstairs radiators which are last to heat up, by closing down the lock shield valves on the upstairs radiators which warm up first, the problem with the boiler becomes worse. Then the boiler can go for 2 - 3 hours with the temp. exceeding the set-point and the boiler cutting out. Normally we ONLY have to wait 45mins to an hour.

I have noticed that when the boiler kicks in if there is greater than 20 - 22C between the flow temp and the set-point, the boiler will usually start controlling OK. E.g. if the set-point is 60C then the startup temp needs to be less than 40C. Any less than this and the boiler overshoots and shuts down.


The word "aired" means lukewarm or tepid. Cheers
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Postby billydotbags » Tue Jan 15, 2008 6:43 pm

Hi
Rosebery made an interesting comment about EU legislation and 6 years responsibility.

I would be interested to establish where this can be found because I have a similar issue ( seperate posting because my search was not effective) and I want to recoup some of my costs from a well known large company.
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Postby rosebery » Tue Jan 15, 2008 7:00 pm

The I definitely think you need him back. He changed it - he should fix it.

Cheers
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Postby rosebery » Tue Jan 15, 2008 10:49 pm

"Rosebery made an interesting comment about EU legislation and 6 years responsibility"

Bit off topic but it does apply (via the backdoor of course) to goods and services as I understand it. So when Brand X sells you a washing machine tell them to place their extended warranty cover elsewhere because if the unit isn't "fit for purpose" 5 years and 11 months after the event they have an obligation to fix it.

Cynic that I am I'm wondering if a well known purveyor of boilers has introduced their "free 5 year warranty - just ask" as a marketing exercise because they have to conform anyway.

Yes it also applies to services!

Cheers
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