Help with Megaflo/Vaillant EcoTEC 415

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Hi there - newbie here looking for some help.

I am not gas safe registered, and not looking to do this on a DIY basis, but I need to know what to tell an engineer when they visit. The boiler is on a Corgi service plan/warranty (which I will discontinue soon).

Last summer the property had a refurb. It's a small property, and prior to the refurb it had a standard HW tank with a header, and a CW tank in the loft. When converting to mains, I had the option of either replacing the (fairly new) HW boiler with a combi, or replacing the HW tank with a Megaflo. I did the latter, opting for a 125l.

This was fitted, and the boiler tested. The fitter noted a PCB fault on the boiler as it wasn't responding to a call for heat, but test mode worked ok. There were no rads installed yet.

Called Corgi out, who took a look and immediately said it was because there were no rads, boiler is fine. They would come again when the rads were on if there was still a problem.

Refurb carried on, and unfortunately the wall stat went into the skip, but the rads went on. Still no response on a call to heat (test mode worked ok, and rads heated when valve turned on manually).

Called Corgi out, who took a look and immediately said it was because there was no wall stat. They said they'd come back if we replaced the controller and there was still a problem.

Had the controller replaced with Honeywell Evohome (it's going to be beneficial to control this remotely). Boiler still didn't respond to a call for heat.

Called Corgi out, this time they sent an ex Vaillant engineer, who tested the boiler a bit more thoroughly. He said there was nothing wrong with it, but that it wasn't wired up to the pump properly (this came as part of the Megaflo). He told me that when the boiler is new, there is a jumper between two points on the PCB which is sometimes removed, and if I wanted heat he could put it back, but there would be no overrun. So, he put it back.

Now, the boiler does seem to respond - pump kicks in and the flame goes on. However when the call for heat stops, the pump stops but the boiler does not. This results in an overheat lockout, and I'm not sure it's that safe.

So, in total 5 separate gas safe engineers have been involved, I've had no proper hot water or heating since last summer, and I just want to get it sorted out. I've done a search here for an engineer, but there are none in the area (CO14). Any clues would be very welcome. I will make sure whoever looks at this is ok for unvented. The original fitter is nowhere to be found.

Thanks!

John.
 
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From my little knowledge, the jumper that is usually removed is the 24v link if you are not using Vaillant controls. That has been done to mine but I still have a pump overrun.
 
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How hard would it have been to wire it properly to begin with?
 
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He told me that when the boiler is new, there is a jumper between two points on the PCB which is sometimes removed, and if I wanted heat he could put it back, but there would be no overrun. So, he put it back.
He has put the low voltage link back in, you wont have any control of the heating except at the on off control manually, there is nothing wrong with the boiler, your controls have not been wired up correctly, the pump must be wired into the boiler, all the advice the visiting so called engineers have given is false
 
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He has put the low voltage link back in, you wont have any control of the heating except at the on off control manually, there is nothing wrong with the boiler, your controls have not been wired up correctly, the pump must be wired into the boiler, all the advice the visiting so called engineers have given is false

Thanks Ian, I think this (and the last engineer) is right. I can't see any wiring going back to the boiler, and I don't think that's correct.

It's a 125SF (SystemFit).

Any pointers to how it should be wired up would be very welcome. I just want to make sure the last visit by anyone is the last visit before the next service. Every time someone visits it's a 250 mile round trip for me!
 
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Any barely competent heating engineer will know how to wire up a system like that. When your phoning round for an engineer just ask them if they can wire an S-plan system up. Using insurance companies who rely solely on random contractors is rarely going to have quality engineers show up at the door. Tell him the switch live from the zonevalves needs wired back to the boiler as does the pump, and an Autobypass valve fitted if there isnt one already there
 
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Do engineers supplied by an insurance company put right design/installation faults or do they just fix correctly installed systems?
 
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Do engineers supplied by an insurance company put right design/installation faults or do they just fix correctly installed systems?

Never heard of insurance that would fix anything incorrectly fitted. Not that many could.

Not wanting to tar everyone with the same brush, but as a general observation in my experience there will be very few good engineers working for insurance based companies, and the ones they do have will probably be under heavy time pressure to get x number of jobs done a day without spending much on parts
 
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So, to continue. I managed to find a local that had a G3 certificate for unvented. I invited him for a look, he said he'd been there before, didn't like the look of the builder and blocked his number. He looked at the wiring, said it might all need to be redone but would cost quite a lot (this is a system fit Megaflo which comes with the majority already done), said he'd let me know and left. I've not heard from him since.

Yesterday, Corgi came to service the boiler (annual inspection) and said they won't do it because the system in its entirety doesn't work. Fair play I think, although the boiler itself runs fine, and can be operated in 'test' mode. While he had the boiler open, I took some pictures of the electrical connection.

The white wire comes from the megaflo, and it shows LN and E are connected to the boiler, but the grey and black wires have just been left hanging.

The plumber that serviced it wasn't willing to change anything (even for extra cash). He wasn't sure, which is fair also.

He's the 7th engineer to look.

He did call his mate (electrician) who was familiar with Megaflos. He wondered if the fact that the boiler was originally conventional (changed to system) meant that it wouldn't be compatible with a megaflo? (to be fair, again, his mate couldn't see the panel and was on the phone). If that really is a problem I won't hesitate to replace the boiler.

Still desperate for advice. The people in those parts are a bit unusual, and tend not to trust outsiders.
 
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the boiler itself runs fine, and can be operated in 'test' mode.
That is not a "Test" mode it is a controls over ride the boiler is telling you the external controls are not wired correctly, hardly a big job to a tradesman, never use a builder or allow a buider to employ a heating engineer, they are as tight as two coats of paint and will cut every corner they think they can
 
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