New condensing boiler installation - truth or lies

wrote:

I think that considering that condensing boilers have been in widespread use in much of the rest of Europe for 20 years, if this was going to be a problem it would have become apparent long before now.
--

.andy

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It won't be either, as the water vapour from the flue is created a second or so before being emitted.
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Thought it had to be the 'fumes' from stagnant water kept at a highish temp and breathed in a confined space? Like from water cooled air con?
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Dave Plowman snipped-for-privacy@davenoise.co.uk London SW
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Nah, it often comes through the DHW supply and out of the tap or shower.
However, air conditioning condensors are often in the 20C-45C critical range as well, so air conditioning is a major player, too, particularly in the larger outbreaks.
Christian.
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wrote:

Nope. Above 60C and it is killed off.

Nope. Spay from open vented cooling towers can disperse the contaminated water about the place.

Not quite. Open vented a/c cooling towers. They are now all sealed.
1/10 Must try harder.
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Yes, pet. Which is why domestic hot water is supposed to be stored above this. Don't you know anything?

In the open air?

They should certainly be.

No star for you either.
--
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wrote:

..the Plowman man he calls me pet ..of inverted gender he must be set ..he gives us info we don't need to know ..down our throats he rams it so
..instictively you will spy ..in newsgroups with DIY ..attempting wisdom this fool will try
..the info's so poor tis clearly true ..so how does this garbage affect you?
..well take no heed of babble and drool ..as this one is a confirmed fool
..he marches around in CAT boots of yellow ..this strange brain damaged sort of fellow
..misadvice he has lots to say ..so don't give this yellow booted half-wit the time of day
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On Thu, 30 Jun 2005 13:59:26 +0100, Dave Plowman (News) wrote:

My understanding is that you need a body of warm water standing around exposed to air. Condensing boilers have only a little amount of water in the trap, which is mildly acidic and anything which comes in from outside is going to get zapped in the burner.
--
Ed Sirett - Property maintainer and registered gas fitter.
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Mine too.

Plus presumably on a hot day with the boiler not in use it would soon evaporate away anyway?
--
*If Barbie is so popular, why do you have to buy her friends? *

Dave Plowman snipped-for-privacy@davenoise.co.uk London SW
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On Thu, 30 Jun 2005 13:59:26 +0100, "Dave Plowman (News)"

Hi,
IFIAK the water has to be 'aerosolised' into a spray at some point.
cheers, Pete.
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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.
--
Andrew Gabriel

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Divert the flue into a chimney stack. That really looks the part.
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babbled like a waterfall and said:

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.
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wrote:

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.
--

.andy

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Martin Evans wrote:

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.

> > 9. It was around 3 days work.
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 Christain said...

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....
--
Cheers,

John.

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On Fri, 17 Jun 2005 17:28:42 +0100, John Rumm wrote:

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.
--
Ed Sirett - Property maintainer and registered gas fitter.
The FAQ for uk.diy is at http://www.diyfaq.org.uk
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On Fri, 17 Jun 2005 14:25:01 +0000, Martin Evans wrote:

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.

Maybe so. 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 <spit>] 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.
--
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A huge thanks to all who replied to my post - many of the comments have been useful in helping me understand some of the issues I had with the visit by BG to look at upgrading my heating system.
This is a long post including an attempt at a summary of what I think I've learnt. Hope it is useful to others as a illustration of my confusions and the problems.
Since BG came to see me my wife found a local plumber and I had also rung a local plumbing comany for a quote. I'm a little nearer a decision but I think the old advice of always get 3 quotes has a big draw back - you get a different story from each one. Not being an expert in heating systems when I'm confronted with differing advice it just lowers your confidence in any of it.
The differences in quotes and advice is vast including (if any are reading I hope my summaries are accurate but if not I either misunderstood or you did not explain it well enough):
o BG suggested keeping my existing system with what seems like a rebadged Glow-worm 30Hxi (thanks Tony). Their quote as BigWallop suggested includes effectively insurance on the new system components and the rest of the remaining system for 3 years (or so I was led to believe - no documentation on that). My shower pump stays so I keep a good output from my shower but still have to put up with the noise from it. Cost 3498 including VAT.
He did not mention possibility of a sealed system or combi boilers.
BG never left my old kitchen where my existing boiler is located, and didn't ask to look at my water cylinder. He did have a laptop, firewire printer and could print out a full quote including colour marketing on the rebadged boiler though.
o plumber 2 (who spent a considerable amount of time with me - what patience) suggested going to a combi boiler (although he would fit a conventional one) - in fact a Worcester Greenstar 440 floor standing combi boiler. He said
a) at 20l/min at 35 degrees C rise, running on mains pressure (subject to testing mains pressure which I'm given to believe is good) it was more than sufficient to match my existing pumped shower and everything else.
b) it would be cheaper to install than keeping my existing system as it was far less components and mostly required ripping (bypassing) existing system out rather than renewing/replacing. Basically, the cold water tank would be bypassed, the cylinder goes, my shower pump goes, electrics are trivial since all that is needed it something to the boiler. I liked the sound of losing my shower pump IF the output at the shower head was as good since the shower pump is noisy.
c) my gas supply to boiler was 15mm and needed to be 22mm. There is no easy way to get a 22mm pipe from the 22mm pipe at the back of my meter to the boiler but it could be run outside (around a 3m run) so long as the pipe was held off the wall.
d) To check the new system would cope/match my existing shower pump I needed to lookup the output from my pump (i've struggles with this as the plate on it quote 3 l/min numbers). Also, I needed to check the spec of the shower valve in my ensuite to ensure it was OK for the new increased standing pressure.
e) we discussed pluming etc and the flue would be routed outside and up the wall to above head height.
f) we discussed reliability of Worcester 440 and he said he had fitted loads, it was good, needed to be serviced once a year and although slightly more involved than a conventional boiler was not time consuming or expensive. On board diagnostics would even detect a leak in my heating system.
g) Mentioning some pipework in concrete floor he was unperturbed, suggesting the increased pressure of my new sealed system was not that high and if existing system was working I'd be OK.
h) I mentioned past experience of combi boilers (over 12 years ago) and he said the worcester 440 was miles ahead of whatever I had then and I would not suffer from excessive reduced flow in winter. He did go on quite a bit about what temperature my shower ran at and how I was mixing alot of cold water with hot to get confortable.
i) he said my existing cylinder (although only 5 years old) was not up to spec since it did not have 2" of insulation (I might have the exact number wrong).
j) all (optional but included in his price) would be in the boiler itself except for a room thermostat. He pointed out the problem with having a room thermstat in the hall where the radiator had a TRV.
k) the worcester 440 had an in built 12l (I think) vessel which had some advantage in the speed in which hot water reached my taps - not sure exactly.
Cost 2600 (for combi boiler worcester 440 floor standing boiler, replacement gas supply to boiler, ripping out / bypassing old system) - sealed system.
o plumber number 2
quote not received yet but it was for a wall mounting Worcester 3XX (something) 12l/min output at X degrees C rise (have not got the brochure).
o concurred with plumber 1 than cylinder was not up to spec. Also said the hot water feed to my shower pump was too high in the cylinder. Also said the cylninder would be better turned through 90 degrees for easier access to valve - fair enough.
o concurred with plumber 1 re TRV and room therm in same room.
o on business of 22mm gas feed to boiler - some needed it some don't - often plumbers size up from 15 to 22 - a bit wishy washy - I was not certain what was required but if a 22mm pipe was required as with plumber 1 it could be run along outside wall.
o on combi boilers he would do a quote for both but a combi would be more expensive since it required ripping out a lot of stuff - somewhat at odds with plumber 1 who said the exact opposite.
o as with plumber 1 he'd need specs for ensuite shower valve as it might not be up to increased standing pressure if we went combi boiler but the myra shower valve in bathroom was certainly OK (I knew this anyway as some tosser who previously installed shower in bathromm before we moved here plumbed it in to the bath supply where the cold water was mains pressure). When it leaked badly I needed to replace it in a hurry and found I needed a more expensive valve to handle the imbalance. Since then it has been replumbed to the cold tank.
o on combi boilers and my concern over loss of output in winter and at my main ensuite shower he said it would cope so long as someone did not use any water elsewhere in the house (whether cold or hot). He recommended not having a combi boiler.
o servicing required for worcester 3XX was once every 12 to 18 months and would cost around 50.
o room thermostat was required and they would not need to put cables in as it was a (cableless) radio one.
o would quote for a powerflush at 395 which would take the best part of a day as it involved connecting to heating system and flushing through plus connecting to each radiator individually. When I suggested this sounded alot (BG quoted 200) he said if the system had been drained recently and was clean I could just ignore that in the quote. They would have to drain the system twice anyway and lfush it with some agent. He didn't try to sell it to me especially when I said the system had been drained more than 5 times in the last 2 years alone and drained out clean (also all of my radiators except one is brand new).
o mains pressure was good in my area and not a worry.
o it cost them 5 to register the installation with Corgi who would send me something I needed to keep as it would be required when I sold my house.
o gas mains was being updated in my area since it fell off too much (and caused some boilers to shut down) early in the morning when all these new condensing boilers switched on.
What I think is a summary of the "true" bits of advice/information I received from BG, local plumbers and this news group are:
o you have to fit a condensing boiller unless you can amass 1000 pts on a rather difficult to achieve scale. Certainly, a replacement boiler is unlikey to achieve 1000 pts.
o plumning - I'm not going there - it seems a contentious issue.
o when moving to a condensing boiler you need a fully pumped system (no gravity fed hot water) - this is law.
o don't have TRV on the radiator in the same room as a room thermostat - also avoid rooms with other heat sources - kitchen, rooms with fires etc Ed.
o condensing boilers produce condensate which is slightly acidic and has to have somewhere to drain away.
o some boilers come with bypass valves, some don't. You can't go all TRVs without a bypass valve.
o 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 - thanks Christian/Andy/John.
o some condensing boilers are modulating so instead of a constant power output they adjust to conditions. Minimum outout of boiler is worht looking at.
o There should be electrical bonding from the meter to the main earthing point in the house. The service bonding ought to be done on the consumer side of the meter rather than the supply as used to be the case.
o water cylinders are subject to building regs and upgrading a system might (or must) mean upgrading the cylinder to current regs. Also, see fast recovery cylinders (this was not mentioned to me by anyone quoting).
wrote:

-- Martin J. Evans Wetherby, UK
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On Tue, 21 Jun 2005 21:14:29 +0000, Martin Evans wrote:

I Maybe wrong but IIRC all Greenstar boilers are condensing.

Initially before the store of HW in the boiler gives out this is likely true. The usability of the system is likely to be good enough except for high speed bath running.

A wall stat (preferrably programmable) will also be needed to comply with current regs.

And properly sleeved etc. etc. All true.

These are not the end of the world to replace later if they are unsatisfactory.

That avoids the need for a terminal guard but no word on the possible pluming problems and air-space wars.

Fair comment.

See my previous post, however a positive attitude has much to commend it.

Fair comment. This boiler has good performance at the expense of floor space, size and weight.

Possibly true.

The TRV must go. As discussed.
k) the worcester 440 had an in built 12l (I think) vessel which had some

See 'f' and 'a' and 'h'

Probably about right.

Someone who having got a powerflush gadget actually wishes to used only when needed, a rare event, a mark of honesty perhaps?

Actually 4 by phone and 2.50 online. Hardly worth itemising really. As to whether you _really_ will need it when you sell - who knows. It is a legal requirement to register the exchange of a heating appliance with building control it is done with this.

Some condensors are quite sensitive to under-pressure others are very tolerant. Condensors use no more gas and possibly less than non-condensors. Combis tend to place bigger peak demands on the supply network. However if the mains are being fixed in your area what's the problem?

Yep
Yep
Just to be clear . TRVs are needed nearly everywhere. The roomstat is needed somewhere but not with the TRV - in the hall is a good place. remove existing TRV if needed.

Yep
If the boiler says it needs a bypass you must have one TRVs or not.

Yep, but go for the room stat. The alternative gear will not be cheaper, people will be less familiar with it. A programmble room stat can provided an accessible heating control.

I don't think you'll find any fixed power modern boilers condensing or not. The lower minimum the better. Provided the HW heating is OK (combi). If you co for a cylinder then I suggest calculating the heating requirements and then selecting the right sized boiler again lloking at the minimum.

Yep
A compliant cylinder is a fast(ish) cylinder.
Both plumbers seem to be saying the right sort of things give or take a few details. The second one wishes to fit a cheaper lighter simpler combi with much less HW output. Still good for shower (but probably not as good as what you have with a pump).
If the wiring from the hall to the boiler is awkward then the 50 extra for a wireless room stat could be worth the extra.
--
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The FAQ for uk.diy is at http://www.diyfaq.org.uk
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You are righht.

It will fill an average bath quite quickly. It is designed to do so.

And liberates an airing cupboard.

They use a lot less gas than non-condensers, that is why the government has legislated in favour of them.

not.
There are a few around. They are superb for mating with thermal stores.

Part L is not fast, just faster than before.

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