New condensing boiler installation - truth or lies

[Martin Evans]

I've had a British Gas man around today to quote for a new condensing boiler. My existing set up is:

o boiler - very old - over 25 years, wall mounted. Flue straight out back to outside above head height (about 5-6ft to next doors house). o gavity fed hot water with thermostat on tank, controlling valve (motor currently broken so manually fixed open although I have a new motor for it) and boiler o water tank in loft feeding central heating o one room thermostat in hall o most (not all) radiators with TRVs - radiator in hall where room thermostat is located does have a TRV. o newish (3 years) programmable controller with separate CH and HW settings and 1 hour, overrides. o relatively new (3 years) myson cp53 pump.

During the conversation he told me:

1. it is against the law to not fit condensing boilers now. From other postings this would seem true.

1. They would remove the room thermostat as it was bad to have it in a room where radiators have TRVs. Other posts to this group seem to suggest having a room thermo is OK but not to have TRVs in the same room.

2. When I said I wasn't sure if we had a bypass and if we went all TRVs I thought we'd need one he said all their condensing boilers come with a built in bypass.

1. Regarding placement on the boiler he said manufacturer specs said their must be at least 600mm space in front of the boiler although it was OK in a cupboard so long as with the doors open their was 600mm in front. As a result he suggested installing it around the corner from where it is now.

2. Our gas meter was not earthed and so they would have to earth it all. I'm not this is true since I remember a large earthing strap behind the gas meter where the pipes come into the house - I cannot investigate this now.

1. condensate from new boiler was not a problem since the boiler will be sited next to a soil pipe.

2. our system was wrong be cause there is not at least 1.5m between the top of the boiler and where the pipes go into the cylinder. This would cause our boiler to switch on and off alot when only heating hot water.

1. conversion from gravity fed to fully pumped was a time consuming process. Some sort of air valve would have to be installed - I'm not sure exactly about this. The system would have to be fully pumped which mean installation ot 2 new valves and pump.

2. It was around 3 days work.

1. the quote left has a "the effects of pluming have been explained" but they never were.

2. He criticised the current electrical installation a lot. Wrong cable used throughout - should all be flex - and told me a horror story about a house fire near us caused by wrong electrical installation where the insurers were not fully paying out after identifying sub standard electrical fitment of halogen lighting.

1. When I asked how he would calculate what size of boiler we'd need he said he didn't need to as it would be a modulating condensing boiler which constantly monitors the exit and return water temperature and adjusts automatically. I did not think this was a satisfactory answer since clearly if he fitted a 1KW boiler it would not sufficient (absurd example I know).

Needless to say I was less than impressed but then came the:

Total quote was for £3498 including VAT (and £100 trade in discount) with some significant numbers being (not including VAT):

British/Scottish Gas 330 HE Condensing Boilrer (inc labour and installation) £1559 specialist building work (3) £174 can't imagine what this was other than repositioning flue connect boiler electrics and test £64 glow-worm Xi std horizontal flue (800mm) £154 glow-worm Xi flue extension (500mm) £28 glow-worm Xi 90 flue elbow £31 radiator valves (15mm angled W/H & L/S) £26 Now he has left I don't understand this as we never spoke about adding radiators or valves. controls pack (2*22mm 2Port) Prog. (UP1) £307 convert to fully pumped 22mm (5mtr head) £312 powerlush - £195 install ME bonding £112 exectrical and mechanical supp bonding £79

there was other stuff like waster disposal, pipe insulation, fit pipe insulation etc.

I was somewhat surprised by the size of the quote and the cost of the boiler - seemed pricey to me.

Any useful comments?

Martin

-- Martin J. Evans Wetherby, UK

[BigWallop]

What type of guarantees do you get with all this? Are they also providing break-down cover for the first X amount of years on the whole installation?

Have you checked out the price of the boiler on the web?

[Tony Bryer]

I think that we may presume from the above that he's proposing a rebadged Glow-worm. A Glow-worm 30Hxi is £795 including VAT at

you need £213 of flue extensions is doubtful

Seems typical BG gas price to regular readers here

[Martin Evans]

I think he said 3 years included but I can't find that info in the quote.

The boiler is exclusive to British Gas - The British Gas 330, so I can't find it elsewhere - unless someone else knows better.

Martin

-- Martin J. Evans Wetherby, UK

[Christian McArdle]

Well, there are exceptions, but these are unlikely to apply to you,.

You need a "boiler interlock" that completely turns off the boiler when the house is hot. Normally this is supplied by the room thermostat. If there is none, another method must be used, such as a flow switch on the heating circuit. Did the installer indicate how boiler interlock was intended to be achieved?

Without knowing all the boilers they supply, it isn't possible to say. Some boilers have internal bypass, some don't. However, there's no reason to disbelieve, really. You'd need one even without all TRV, as you are going S-Plan.

Sounds normal, assuming the move around the corner is to improve aesthetics, or flue location.

Sounds good. Better than some where they use a "soak away", which is a euphemism for sticking a bare pipe out of the wall which rots away your patio.

The vertical height of the boiler and cylinder is no longer relevent, as the system MUST be converted to fully pumped by law. Fully pumped systems don't care about heights.

There are other methods, but the 2 valves and the pump is one of the most common, simplest and reliable. It is called 'S' Plan. Some of the conversion will be to make it a sealed pressurised system, rather than gravity fed. This is well worth doing.

Could well be.

The exhaust terminal will shoot out loads of visible steam, especially in winter. This may seriously annoy the neighbours, even though the exhaust is actually cleaner and less poisonous that the invisible plume of older boilers.

There is no need for the cabling to be flex. Indeed, apart from the final connections to any immersion heaters, external pumps or zone valves, fixed T&E wiring is actually superior. Flex is often used because it is easy to get multicore versions which are more convenient, though.

Ignore friend of a friend horror stories. Almost certainly not true.

He is actually correct. Most modern condensing boilers have a much greater maximum output than any normal house requires. (Some manufacturers have recently produced throttled back versions that might struggle on a big house, though). You need to have a 10 bedroom 1660s place with no glass in the windows to exceed the capability. (Well not, quite, but if the calculation did show a bigger boiler was needed, the correct approach is to fix the house insulation, not fit a bigger boiler).

Not actually that bad for a BG quote. Still much higher than a good local engineer, but not in their normal stratispheric regions, given that the quote includes lots of additional work to the actual boiler swap, such as the fully pumped version, movement of the boiler, updating of controls etc.

The Glowworm HXI/CXi/SXi is the boiler that is currently rescuing Glowworm's reputation. It is certainly not scraping the barrel by going for a cheap boiler.

Well, BG always give the most expensive quote. Make sure you phone round some local non-chain places.

Christian.

[EricP]

Yes, been down the same amusing road. Get anybody else to quote and you should knock £1000 off the job. Get three people to quote and you should arrive at a fair price. Put the BG stuff in the bin.

[Martin Evans]

have is some marketing stuff from BG telling me how good it is. SEDBUK A rated, NOX class 5 emissions, SS heat exchanger, on board diagnostics, "Continua" electronics allowing the boiler to continue where others may fail (hmm), adjustable for my future radiator needs, frost protection.

I didn't get that either. The boiler is only moving round an inside corner so it will be less than 0.5m from the outside wall and £213 + VAT for flue extensions seemed rediculous.

Thanks for th response.

Martin

-- Martin J. Evans Wetherby, UK

[Martin Evans]

Chistian,

Thanks for the >> 1. it is against the law to not fit condensing boilers now.

So I gather. It would be really difficult to argue in my case.

Not that I recall. A question I'll ask of him.

Actually moving it round the corner increases flue length. The problem occurs because the current boiler is on an end wall right up to a boxed vertical section carrying the soil pipe, other pipes and pump. On the other side of the corner my wife wants two double wardrobes and if the boiler was replaced in the current position there would only be

29cm space in front of the bolier. He suggested putting the boiler on the wall to carry the wardrobes inside one of them. I assumed the corner flue piece he quoted for was to take the flue round to the existing flue exit hole which is why I was also questioning the "specialist building work".

He didn't explain it must be converted to fully pumped he made it sound like our system was wrong and the new one would overcome this error.

I think this is where this "air vent thingy" come in - it was something to do with keeping our system open. He definitely said they would not be converting it to sealed system because some of the pipework is in concrete and a leak would be a big problem.

"shoot out" does not sound so good. It is less than 3' to a fence and then less than 3' to my neighbours house with the fence lower than the vent. Shooting out whilst someone is walking down the side of the house (either on my side or my neighbours) wouldn't be good.

The valve behind the cylinder is connected to a junction box by T&E. From here 2 T&E come down to another juntion box where flex goes off to the boiler and programmer. The immersion heater is flex. It was the T&E down the boxed section from my airing cupboard to the jn box below he specifically tutted at.

That is very good to know. This one worried me the most.

Have done so.

Thanks again. Your post has helped sort a few things out for me.

Martin

-- Martin J. Evans Wetherby, UK

[Andy Hall]

Generally this is the case. There is a system for exceptions based on location and work involved to site a condensing boiler which applies points to a number of difficulty issues. However, if it is a replacement for an existing wall mount boiler then you are unlikely to meet the exclusion criteria.

There has to be a means of locking out the boiler when the heating for the house is satisfied and this normally does mean a room thermostat. It should not be in a room containing radiators with TRVs because the two will tend to fight. The correct solution is to remove the TRVs not the room thermostat, although the latter could probably usefully be changed to an electronic optimising type.

Many do, and possibly all the ones that they sell, but I am not sure that this is universally the case. The manufacturer installation instructions will specify whether a bypass is needed or not.

The manufacturer's installation instructions are the definitive source of space requirements.

There should be electrical bonding from the meter to the main earthing point in the house. The gas supply should not be used as the electrical earth.

Correct. It needs some from of suitable entry into it, though.

If the existing system is using "gravity" circulation to heat the HW cylinder then the vertical vs. horizontal pipe runs can matter. However, modern boilers, expecially in a new system like this are used fully pumped so it doesn't matter.

Waffle. It might be worth installing a new fast recovery cylinder to make the most of the pumped arrangement.

Could be.

You may get a plume of water vapour from the boiler flue under certain conditions. These are typically most noticable when the boiler runs flat out on a cold day. If the flue is facing the neighbour's boundary and is close to it, then this may be an issue. However there are flue types for some boilers that can be routed over several metres and can exit in a completely different place. Some can even be 50mm high temperature waste pipe. Of course BG might not have these on their list.

Possibly. Certain cables should be flexible types. However, the way it's described sounds more like FUD to justify higher quote.

To an extent that's true. If the current boiler is adequately heating the house, then fitting one having somewhat more capacity is fine. They do modulate their output over a wide range.

It is a high quote for this. It doesn't really matter how they've carved it up, the overall price is what is important. I would have thought that £2000 was nearer to a reasonable target for a good boiler and the works described - more if you change the cylinder, and I would suggest that, because the water will re-heat faster and the boiler can return to heating the house sooner. With most control arrangements, the HW has priority over the CH, so you really want to heat the water quickly (it is more efficient if you can transfer a lot of heat quickly) and then return to CH.

[John Rumm]

Mostly true... from the sounds of your setup it is not worth worrying about the possible get out clauses.

Personally I would change the room stat to a programmable one and remove the TRV. You still need some form of interlock to shut off the boiler when the whole house is warm.

Could well be true for theirs...

Just so you can get the case off basically. Can you not do that in the current location?

The service bonding ought to be done on the consumer side of the meter rather than the supply as used to be the case.

This sounds like he is confusing a bit of old gravity fed sales patter... for a fully pumped setup it will make no difference.

It might be worth investigating a new fast recovery cylinder however. If you current one is old, remember the things don't last forever. A fast recovery one will also be able to swallow more of the boilers output. THe modulating function of the boiler however ought to prevent cycling anyway.

Sounds plausable - depending on what pipework needs doing. Took me about

4 days, but that included stripping out all the old tanks as well.

Like Christa> 11. He criticised the current electrical installation a lot. Wrong

You can ignore that I would guess.

Since you are not looking at a combi where the output power will directly dictate your hot water flow rate, it is less of an issue. As long as you have "enough" the modulation will make a decent job of matching the actual output to the demand. It is sometimes more useful to ask what the lowest power output of the boiler is. Ones that can modulate right down to 4 or 5kW being better than ones that only go down to say 12.

For BG that sounds cheap... 5.5 would be closer to their normal!

Probably fair for the boiler on its own...

But you would expect this to be included in the above...

and this

probably don't need those - especially if you keep it in the current location.

He may be talking about replacing the old lockshied valves with new ones. Some of the older ones can weep when converted to pressurised operation.

Sounds a bit much...

hmmmm...

perhaps

excessive...

excessive...

I would have thought something closer to 2k would be more like it....

[Ed Sirett]

Almost certainly true.

If the wall stat is in a good place then the TRV should go. A good place for a wall stat: a) Not subject direct heat (from sunlight, radiator, or other source of heat). b) In a room that is representative of the heating as a whole. (i.e not in cooler rooms/ bedrooms/ bathrooms). c) Not in a room with an additional source of heat (not in kitchen or living room with fire)

This invariably makes the hallway and maybe the living room the best places.

They are fitting something modern , so likely true. There is no easy way to go all TRV and comply with Part L.

Find out the model, download the instructions and decide for yourself - it's likely true.

The correct place is on the first 600mm of outlet (your) pipework.

Dropping the condensate into the soil pipe is acceptable.

OK this is the first one I'm unhappy about. The HW cylinder must (same 'must' as q1) be a fastish recovery unit (less than 25mins from cold IIRC). Such a cylinder will likely be able to take the bulk of the boiler's output. In my own home a cylinder reheat cycle take c. 10mins this consists of

60seconds of 25kW follwed by c. 10 min of ever reducing power output till the cylinder stat call time. The cylinder is adjacent to the boiler and is about 1m there and 1m back as the Irish say.

True. True. True. But any good heating engineer is going to recommend the same. Pump is likely in the boiler.

True. for 2 experienced guys.

So they messed up.

However, I thought that by the book the wiring for heating controls should be in cable with flex outlets adjacent to each sensor/appliance. Usually they are just done in flex throughout . Cable _is_ incorrect.

OK On the [mandatory ] C&G energy course some of us locked horns with the tutor on this one. I maintained that the _first_ question to ask was "How well did the heating work [before it broke!]" and this along with experience and further questions like "Was there anywhere always too hot or always cold". _Then_ you could run through the calculations to see if you need to size up or down a bit (or even a lot).

The tutor maintained that you run through the standard assessment calcs then size the boiler and ignore the existing installation (what utter bollocks).

It is true that modern boilers are considerably more forgiving of being over-sized than older models.

The BG guy here is plain wrong and would fail a C&G assessment.

7> with some significant numbers being (not including VAT):

An independent fitter if you can get hold of one should be around £2250 give or take. They are Fleecing it heavy on the controls. I'm nigh on sure you can buy the whole lot for just over £100 (on a bad day).

I can't be bothered to look up the boiler on the net but I'd be surprised if it's much over £700 + VAT.

The 'advanced' controls are subject to reduced VAT (5% IIRC) which is just tokenism on the part of the treasury, IMHO.

[Ed Sirett]

Having read through the other posts (no one's drivelling IMHO) and your further comments.

It seems that BG are doing two things which I had not realized.

1) They are not going to a sealed system - they are obviously concerned about the state of the pipework in the concrete floor. They are being cautious; if and only if the existing pipework is working correctly and never pumps over and never entrains air then I think on balance they are right. Without seeing the job it's hard to balance the risks.

2) They are _illegally_ not intending to upgrade the water cylinder this is in contravention of the Building Regs. ISTM that the quotation operative from BG is not up top speed on the current regs.

[Owain]

Isn't it water vapour, rather than steam? I think it's quite pretty, especially on a frosty day.

I don't think - although I could be wrong - the flue gets dangerously hot. AFAIK it's acceptable to have the flue somewhere someone walks past provided there's a wire cage over it to prevent direct contact.

What must be carefully positioned is the pressure relief outlet, which shouldn't shoot out anything in normal circumstances, but will shoot out boiling water and/or steam if Something Goes Wrong.

Owain

[John Rumm]

The flue gas temperature will be significantly lower than with a conventional boiler. So it is better to get hit by the output from a condensor than a conventional boiler. The only real difference is it is cold enough for the water vapour to be visible.

[John]

Steam is actually invisible (and highly dangerous as a result).

Glow worm have recognised the plume as being a problem and make a kit to extend the discharge upwards and away from the flue wall exit point.

The cage is a throwback to flue terminals which got hot enough to brand you. A cage was to stop this happening so as a result you got a criss-cross wire pattern burnt into your flesh as a result The requirement is still included in the GSIUR of course

True

[John Rumm]

I find it supprising that people get so upset at the sight of a bit of water vapour... They must get really scared when they make a cup of tea! ;-)

[<me9]

What I wonder about condensing boilers is whether the low temprerature plume can spread legionella. Can water sit anywhere at a suitable temperature to allow growth of the bug. What precautions need to be taken to prevent this. Has a risk assessment been done?

[Andrew Gabriel]

Yes. The plume is actually a fog -- tiny condensed water droplets suspended in air. Steam is invisible, but often forms a fog at the boundary where it mixes with colder air. A condensing boiler should not be emitting any steam -- the flue gases aren't hot enough (even when it's not operating in condensing mode).

Likewise, required clearances below plastic drain pipes made me smile, when the flue itself is a plastic drain pipe;-) I had to go through the rather pointless task of moving the rainwater pipework when I installed mine.

[Andy Hall]

Several points.

- In the area of the burner the temperatures are considerably higher.

- Flues are normally arranged with a slight slope back towards the boiler for nominally horizontal runs so that water condensing in the flue goes mainly back into the boiler. This is also to stop it dripping out onto the ground outside.

- Internally in the boiler, there is an arrangement for the water to run down into a trap from where it then drains out. Hence there is not really a place where it will remain stationary for long.

- The condensate water is mildly acidic.

- Condensing boiler technology has been in use elsewhere in Europe for

20 years and there are not large outbreaks of Legionella reported as a result of its use.

[Andrew Gabriel]

My Keston, which ran at around 45C flow through most of the winter, did manage to grow something a bit jellyfish like in the bottom of the heat exchanger (which would have been slightly cooler than 45C). This then blocked the condensate drain causing the heat exchanger to start filling up until it was making quite a gurgling noise and failed to light. I didn't conclusively prove if the jellyfish like thing was animal, vegetable, or mineral and it was broken into small pieces by the time I got it out.