New boiler was chem flushed at installers recommendation

[dane606]

Hi there

3 weeks ago had a boiler installed - the enigineer said they didn't recommend a power flush. The DHW wen't last week, we've had the manufacturer service team out who said the heat exchanger needs replacing as is full of green water and gunk, causing the boiler to lock out.

The installer is now happy to add more inhibitor after draining and replace the heat exchanger (but the warranty already pays for the part), but he wants £300 for a power flush (there are 3 rads and a towel rail).

Also, we've been told that the gas pipe going to the 35KW boiler is too small - shouldn't the installer have noticed this? (they chose the boiler in the first place). Pressure goes down to 15.8 when using the kitchen range.

The power flush may well mean no more problems in future, but I think if it was my business (i do have one) then I would be offering it for free since I'd already recommended the chem one and it didn't work (and the customer has already paid for it).

Also, will this kind of gunk damage the magna clean filter?

Any advice greatly appreciated

Thanks

 

[Dan Robinson]

Sounds more like they didn't clean out the chemicals from the original flush. In which case I would say that it is their problem.

Gas pipe should also have been sorted with the boiler. At the time it would be fair of them to charge extra. Now they are on a bit of a sticky wicket.

 

[CBF]

as Dan said but they should have sized the gas pipe before installing the boiler, if it was me i'd tell them to increase the size of the pipe so it is correct foc or you are going to ask for a gas safe inspection, they have installed the boiler to NCS & this is something they aren't allowed to do

 

[Agile]

Is the 15.8 mbar with ALL the range burners turned on?

What was the pressure at the meter when that 15.8 mbar was measured?

Whilst the gas regs do require gas pipes to be sized for ALL burners operating, it is not a situation likely to be found in practice. Regardless the largest gas consumption will be the boiler.

Did you have the range cooker when the boiler was fitted?

Tony

 

[dane606]

Hi Tony - its 15.6 with all range burners on (happens every other sunday). Yep the range was already there, I don't know what the meter pressure was at that point, I don't think they took it.

We had the pipes redone when we fitted the cooker a few years ago, but that was a small boiler (24cDi).

 

[Agile]

It is pointless measuring the working pressure at the boiler without measuring at the meter at the same time.

Its also a common mistake that many RGIs make.

A friend was about to cap off the boiler until I alerted him that without the meter pressure being checked that may be totally unecessary. The meter regulator was faulty!

The pressure at the meter can be 21 mbar +/- 2 mbar.

The pipework pressure loss should not exceed 1 mbar at full load.

The actual working pressure at an appliance should not be less than 15 mbar otherwise it should be classed as At Risk.

That last figure is based on rather historic designs as most current boilerw will work fine down to about 11 mbar or lower. The fear is that cooker burners may go out and leave gas flowing, but modern cookers incorporate flame sensing devices to turn off the gas if there is no flame.

Tony

 

[GrahamT]

What boiler did you have installed?

As some manufacturers allow lower working pressure, i.e Glow Worm flexicom have a minimum of 15mb and Worcester CDi, Si & jnrs allow minimum of 16.5mb.

 

[Agile]

The minimum the makers accept makes no difference to the installer's need to have a maximum of 1 mbar pressure loss in the pipework.

Tony

 

[GrahamT]

The minimum the makers accept makes no difference to the installer's need to have a maximum of 1 mbar pressure loss in the pipework.

Tony

yes & no.

If you have a 19mb working pressure at the meter, 18mb at the inlet valve - Worcester judge a 1.5mb drop from the inlet to the gas valve. A reading of 16.5mb at the gas valve in this instance is acceptable.
As there isn't a test nipple before the inlet valve, you can't measure a 1mb drop, so have to go with a maximum 2.5mb drop at the gas valve.

But, like you say, you need to check the pressure at the meter.

 

[swbjackson]

If the installer is unwilling to rectify the gas pipe sizing issue give Gas Safe Register a call and ask for an inspection. They will normally insist that the fault is rectified.

 

[Bunnyman]

35kw for 3rads an a towel rail how much water r u using

 

[dane606]

we're adding underfloor heating later this year to an extension - I agree its a bit overkill though, but wasn't my choice - just advised!

 

[Agile]

That size of boiler will give plenty of hot water.

Unfortunately it is seriously oversized for CH and will be giving serious short cycling ( and inefficient operation! ).

Tony