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I've been advised from another forum that diynot forum would be more suitable....

We moved into our new build home last September. Last week I discovered the combi boiler's first service was due 21st June, so in order not to have any issues with the two year guarantee, I booked a gas engineer to service the boiler. He came recommended and I agree, he's a gem.

Baring in mind I'm no engineer, I'll try and explain the engineers concerns.

The installation of the boiler:

It appears that where the flue goes outside, the pipe is not cemented in, there's only a rubber gasket. Fumes therefore can easily enter the cavity walls and into our property. Quote on the Notice: "Flue not secure to fabric of the building on the outside".

The flue pipe on the inside of the property is secured by expanding foam. The engineer has no idea if the foam is fire-proof, and the foam stops him testing for any leaks.

The boiler itself:

The engineer was unable to test the boiler ie gas in / fumes out because..... he stated the boiler was way too big for the system at 40kw (we've a 3 bed house with 11 radiators and two showers). While trying to test the system with radiators at full bore, the boiler kept cutting out. So with the help and advice from Baxi, the first of the three sensors was disengaged. This didn't make any difference so the 2nd sensor was disabled, and the system was tested again. The boiler still cut out. There's another sensor but Baxi and the engineer believed it too dangerous to disengage this one.

As the engineer was unable to test emissions, he couldn't finish the service.

I'm hoping the house developer will contact me next week, but meanwhile I'm on a fact finding mission to discover my rights.

1. Obviously the flue pipe will need fixing, and no doubt this should be part of the building guarantee.
2. Can I insist on a smaller boiler? This 40kw one must be heavier on gas than I need, and it's hardly efficient.
3. Can I claim for some of the gas (unnecessarily (?) ) used last winter?
5. Can I claim for the engineer's fees? (btw the engineer said he'll not charge me, but I do think I should pay him and get a refund from the developer).

My neighbours will probably have the same problem as me.

Engineer thought that last June boilers were in short supply due to covid etc., and so he imagined the developer took what stock they could, and that was an oversized boiler.

Any thoughts and advice would be gratefully received. Thanks.
 
What make/model boiler is it? Do you have a hot water cylinder or is this a combi boiler?
 
Probably 10 min job to cement around the flue.
with the system cold and all rads on it should be en time to test emissions and gas rate etc.
 
cross thread said:
Probably 10 min job to cement around the flue.
with the system cold and all rads on it should be en time to test emissions and gas rate etc.
Click to expand...
Thanks for your reply, Engineer couldn't test because the boiler was too big and kept cutting out.
 
If it's a combi then it can be tested by running the hot taps to keep it at full power. The Duotec isn't great for heating efficiency as it has very poor modulation but it would have satisfied the minimum requirements at the time that it was installed
 
Yes the annular space around the flue should be made good outside but that's to prevent anyone pulling the flue out. Fumes are not going to reenter the average property.

As Muggles says the boiler is compliant although definitely not my first choice. Personally I'd look for a different engineer that's not actively looking for problems...

BTW here are the official guidelines

 
Sorry to **** on your parade, but you engineer of choice is not as good as you think, all he had to do was open one or two HW taps and the boiler wouldnt cut out, and sorry to tell you that you have no claim in any way with the builders , you could ask them to seal the flue on the outside but that is all
 
Your lucky to find faults so soon, I was involved with my father-in-law fitting a new gas fire, on removing old one found the flue plate no where near sealed to the wall, I could put my hand through the gap plate to wall. It was fitted same time as mine 1978, however unlike mine he used his most winter days, my central heating had radiators in all rooms, his missed out living room, so he used the fire daily.

I had to plaster the wall so the flue brick could connect to the plate, and to be safe had a gas safe guy to fit it, he sealed the plate with gaffer tape, and as soon as fire was hot, it all pealed off.

However the fault had been there some 40 years, with three owners having lived there, and no one died, however in 1978 doors did not seal well, with had single glazed windows which did not seal well, and no vented tumble drier or extractor fan in the bathroom, by the time my father-in-law died it that triple glazing, UPV doors, and tumble drier pumping air out of the house.

But the main thing is he also had a gas cooker, with no cooker hood, so all exhaust gases from that also entered the house, lucky we no longer have coal gas.
 
ericmark said:
But the main thing is he also had a gas cooker, with no cooker hood, so all exhaust gases from that also entered the house, lucky we no longer have coal gas.
Click to expand...
Cookers do not need cooker hoods
Cooker is a FL appliance.
where did you get this cooker hood gem from
 
If a fuel produces noxious gases when burnt in one appliance, unless due to not surfactant oxygen, then it will also produce same gases with any other appliance, and if the fuel is a hydro carbon, then it will produce carbon dioxide or carbon monoxide and water, the latter if not removed even without the other gases will cause the home to get damp, I know my house would normally show around 75% humidity and father-in-laws around 85% and houses were same design in the same street, next door but one, and he lived alone and two in our house.

Also there is the heat problem, idea is heat goes into the food, but ¾ of the heat from a gas cooker goes into the room, an extremely inefficient cooker compared with electric induction. Since gas is cheaper in winter not a problem, but in summer it can result in needing a heat pump (AC) to remove the heat, and that uses electric, so it then is far more expensive to use gas.

Gas is likely the best compared with solid fuel or liquid fuel i.e. oil, although I question the safety of having a LPG tank in the garden. And until you draw the gas it is a liquid fuel, which you have to sign an agreement to buy from one supplier in most cases to get the LPG tank.

Main advantage with gas is the appliances are cheap, an oil boiler costs a lot more than a gas boiler, and an induction hob or solid fuel cooker cost far more than a gas cooker.
 
1. Obviously the flue pipe will need fixing, and no doubt this should be part of the building guarantee.
Yes, they can cement the flue in place.

2. Can I insist on a smaller boiler? This 40kw one must be heavier on gas than I need, and it's hardly efficient.
No, theres unfortunately no rules on oversizing boilers, I see 40kw combis in 1 bedroom flats all the time. Combis are sized for the hot water output not the heating load. (not that I agree with the practice of fitting gigantic combis, but its perfectly allowable)

3. Can I claim for some of the gas (unnecessarily (?) ) used last winter?
No. Your bills are what they will be,

5. Can I claim for the engineer's fees? (btw the engineer said he'll not charge me, but I do think I should pay him and get a refund from the developer).
You asked him to service it, did he service it? if so you pay him for what you asked him to do.


Its a combi boiler, you would test the flue gas readings on max rate, while running multiple tap outlets to get the heat to dissipate through the taps. The fact hes had to phone baxi on basic testing would suggest hes possibly fairly new/inexperienced.

Its good that hes checking the flue correctly, but the seals are there to stop lateral movement of the flue, not really to stop fumes re-entering as the chance of that happening on any detectable level from an unsealed to the wall flue would be astronomically low.

FYI, fire rated expanding foam is pink, non fire rated stuff is yellow. Although expanding foam at all is not allowed for sealing flues to building anyway.
 
ScottishGasMan said:
FYI, fire rated expanding foam is pink, non fire rated stuff is yellow. Although expanding foam at all is not allowed for sealing flues to building anyway.
Click to expand...


Sorry SGM I think you need to read the TB I posted above.

Do Vaillant not allow you to foam flues then? Lots of manufacturers do...
 
The reason it could have been cutting out, especially on a new build is the heating is likely separated into 2 zones (should be easy to confirm if you have x2 room thermostat’s) and if these weren’t open, could be the reason, but as said, he could have ran the hot water.
 
I am sure the experts will correct me if I am wrong, I am only an electrician, but as I understand it all modern gas boilers modulate, that means turn down, so an over sized boiler will tun down to minimum output, once they can't turn down any more they cycle, i.e. turn off/on/off/on etc, and the mark/space ration between on and off is altered to get required output. So it would not use more gas due to being larger.

Today speed is used to reduce fuel usage, the faster the room heats up, the less time in advance of room being required does the heating need to switch on.

Last house living room had two radiators one 4 kW and one 4.5 kW one being fan assisted, plus a 4.5 kW gas fire, with a cold house, been living at mothers, living room warm within 15 minutes, the whole idea of geofencing was simply not required, we would just switch on heating when we got home.

This house is very different, OK open fire in living room so could burn a few logs, but it takes time to light, and I have never used it, other than as an exhaust for the AC unit, very large room, two radiators, not fan assisted, and even starting at eco setting, i.e. already some heat in the room, to get to comfort setting takes around 2 hours, mainly as ceiling low so don't get natural circulation, really needs fan assisted radiators.

Since now retired and so in house all day, it makes little difference, but when going out to work, idea is to turn off heating, then reheat just before returning, with my three story house and a 20 kW boiler to heat fast I need a lot larger output radiators and set the programmable TRV heads to prioritise so rooms which are going to be used first are heated first, in this old house not a problem, although the heating is in two zones, the flat and main house, the flat is rarely heated, and the house is all one large zone, with each room being a sub zone, so heating can be set to heat office during the day, but not bedroom, even when as built both were designed to be bedrooms.

I would like to say every room is independent, however that is not really the case, as the TRV heads are not linked to the wall thermostat, and unless the wall thermostat switches on, no rooms heat up, so hall temperature has a bearing on all rooms.

And this is the point, most central heating systems are a compromise. The basic boiler and radiators may be good, but it is how we control the system which makes it more or less expensive to run, at building stage the designer can stipulate some very clever systems, as the cost is likely going to be spread over 25 years. So spending £15k on the heating system may be possible. But once built modifying to use less fuel costs a lot of money.

A Drayton Wiser system for 2 rooms is around £200 plus £43 extra for each room, same with Honeywell Evo Home, and Tado this house would need 14 TRV's so £800 for the kit, plus fitting cost. At 70 I can consider around 30 years max, more likely 15 years, so cost is around £50 per year plus interest, and interest cancelled out by cost of living raises, before all the price raises for fuel, I was paying around £250 to £350 per year for oil, so looking for a 20% saving in fuel to be worth up grading.

But in real terms it's more down to upgrade the central heating, or go on holiday?
 
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