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Boiler fires when no demand

View the thread, titled "Boiler fires when no demand" which is posted in Boiler Advice Forum on UK Plumbers Forums.

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cudney1

Hi everyone,

i installed a Worcester greenstar 30CDi regular heat only boiler today, it was a sub contracting job and an electrician wired it up (as part of the contract). I turned it on and tested everything was working, once i had commissioned it i turned the controls off at the programmer but the boiler kept firing on hot water only even though there was no demand.

it was late in the day and the house is unoccupied so i pulled out the fuse isolated the gas and came home. I've had this problem before when fitting a Baxi Solo, i managed to isolate the problem to the pump. For some reason a voltage was being sent back through the pump to the orange on the 3 port.

The pump that was faulty was a Grundfos UPS 2 15-50/60 pump, it is the same pump on this job.

I'm just wondering if anyone else has had problems with these pumps or The LP522? i believe there are some faulty LP522 out there.

I'm going to have another look Monday and see if i can solve the problem but any info from you guys would be very helpful
 
Without sounding daft, why bother. It's obviously the sparks fault. Use your time to earn money.
 
Yeah i know what your saying but i want to find the fault, he did get the common and the satisfied from the cylinder stat round the wrong way, i told him to stick to the drawing inside the wiring center so anyone in the future would have some reference but hes was a bit cocky and didnt understand why he had to put links in. Basically i dont think hed been on the tools that long
 
The only way in my mind is to rip it out of the box and star again. But why should you do it?
 
I will counter charge the contractor for the work so i will be paid, but sounds like a good plan at least i can trace back any fault that way.

But have you come across any problems with the new Grundfos UPS2 pumps?
 
cudney1 said:
I will counter charge the contractor for the work so i will be paid, but sounds like a good plan at least i can trace back any fault that way.

But have you come across any problems with the new Grundfos UPS2 pumps?
Click to expand...

Ashaned to say it, but I haven't used one yet. Are they still three wire?
 
Yeah still 3 wires but they modulate, to be honest i miss the old style. More tricky to clip the wires in if in a tight spot
 
cudney1 said:
Yeah still 3 wires but they modulate, to be honest i miss the old style. More tricky to clip the wires in if in a tight spot
Click to expand...

Cant be the pump then, if its only three wires. Probably got the switch live and permanent live mixed up. A lot of sparks don't get pump over run.
 
i was thinking the same thing, theres a link in the boiler which i reckon hes left in, its one of those things which is going to bug me untill monday morning lol
 
Or hasn't broken the link enough in wiring center ( Honeywell muppet box) wire the pump before u fit it! The ups have a plug which comes off the pump?? Wilo are flippers??
 
Yeah I had it. The pumps blow the relays in the time clock. Grundfos do a power cable with some kind of surge protector. The pumps pullnto much power when the start
 
In general there are only three wires that control a gas fired boiler, (1) a permanent live (2) Neutral and (3) a switched live the permanent live is always there to ensure power for the fan run down, pre and post purges and also the power for the pump which is controlled via the boiler run down timer, this removes residual heat after the boiler thermostat is satisfied.

The switched live is turned on and off via the timer or zone valve, if the boiler is running all the time then the switched live is on, this is a 1 minute job to test, BTW if you take the front of the boiler case off to get to the electrics what's the score on GSR.

My daughter has a Potterton boiler and her user manual shows the led status if there is a fault, you wont find the leds when you drop down the front door, they are behind the boiler case, two screws and remove the case and there are the leds, what's all that about Potterton, destine to confuse.
 
happyflyer said:
In general there are only three wires that control a gas fired boiler, (1) a permanent live (2) Neutral and (3) a switched live the permanent live is always there to ensure power for the fan run down, pre and post purges and also the power for the pump which is controlled via the boiler run down timer, this removes residual heat after the boiler thermostat is satisfied.

The switched live is turned on and off via the timer or zone valve, if the boiler is running all the time then the switched live is on, this is a 1 minute job to test, BTW if you take the front of the boiler case off to get to the electrics what's the score on GSR.

My daughter has a Potterton boiler and her user manual shows the led status if there is a fault, you wont find the leds when you drop down the front door, they are behind the boiler case, two screws and remove the case and there are the leds, what's all that about Potterton, destine to confuse.
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must be competent person to do that Happyflyer
 
This was a simple question about the Potterton, I just wondered if you have come across it yourself, if you were talking to someone one the other end of the phone with a fault and you said which LED are on they would say there are no LEDS , Worcester have there LED under the drop down panel, just a bit funny to me or suspiciously or a clanger on Potterton's part.
 
SafeGasInstall said:
I /we dont ask for LEDs been on or off ! there is sequence of operation on boilers ......
Click to expand...

That's not the way to do it..... When initial enquiry on phone u should ask , postcode and what car they drive..... Makes diagnosing repair much easier.
 
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