boiler insulation

[Yorkie]

The idea is to insulate the free standing boiler to reduce heat losses from its water jacket by means of a modern insulating blanket that is a similar material to shuttle tiles. This will fit inside the boiler sheet metal casing and be clipped against the outside of the boiler, obviously leaving gaps where there are air intakes, flues and other combustion access. This should considerably reduce losses from the boiler shell.

Your thoughts Gents?

Ed

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Just a few observations on those comments.

1) Very little heat is emitted from a modern condensing boiler. The casing is warm to the touch, but certainly not hot. I've just checked our Worcester Bosch and the casing is 26C at the front, and 24C at the side. The flue outlet is 24C, but then the outer part of the flue is the cold air intake.

2) Boilers are usually sited where any heat given off isn't waste heat but useful heat - utility rooms, garages, lofts etc, (no bad thing to have a little heat up there, with all the plumbing, however well insulated it might be). Admittedly when sited in kitchens, the heat isn't always welcome, but wherever a condensing boiler is sited, it will emit far less heat than your old Glow Worm boiler. Apart from that, I wouldn't personally modify a boiler by fitting insulation inside the casing as the boiler has been designed, tested and approved without such additions, and it's difficult to predict what effect such modifications might have on the operation of the boiler.

3) In terms of making economies on heating bills, do bear in mind that for every hundred pounds of gas you are using in your Glow Worm, about £40 of that is going out of the flue into the big wide world as your personal contribution to global warming, (not to mention other heat losses if you don't have such things as double glazing, cavity wall insulation, [unless solid wall of course] and at least 30cms of loft insulation). With a condensing boiler, that £40 loss per £100 of gas used drops to about £5 - £10. Your Glow Worm also has a permanent pilot operating 24/7/375 even when the boiler isn't calling for heat. It has to do that to keep the thermocouple energised and the main gas valve operational. A condensing boiler pilot light only comes on when the boiler is operating, and serves as a flame failure device. The sequence of events when a condensing boiler comes on is broadly as follows:

i) The fan comes on to purge the combustion chamber and introduce fresh combustion air.

ii) Gas passes to the pilot, and ignition sparks ignite the pilot. A flame will conduct and rectify AC current to DC, so a very small AC electric current passes across electrodes through the pilot flame, and provided a pilot flame is indeed present, the current is rectified to DC, so when the flame protection circuitry sees that DC current, it brings on the main burner. No DC current present? - no gas to the main burner as there would be no pilot flame to ignite it.

iii), whe the heat requirements are satisfied, both the main burner and the pilot light go out. The fan will continue to run for a short while to prvent the cool the boiler down, and there will be a pump 'over-run' for a short while to ensure that the hot water in the heat exchanger goes into the heating/hot water circuits rather than being retained in the boiler.

The condensate drain within the boiler has a reservoir into which electrodes are present at above the level of water when the drain is working properly. However, if the drain is blocked, (iced up for example), the water level in the reservoir rises, shorts out the electrode and tells the boiler control circuitry that the condensate drain is blocked.

That's a very broad generalised and simplistic explanation, and these days, is about as much as I know, or for that matter, want to know, about modern gas boilers!

I'm always dismayed - especially when I drive round the North Cicular in London - to see very long condensate drains in exposed positions on outside walls, contrary to all sensible advice by manufacturers. It's quite commonplace to see white 22mm condensate drains on outside walls for two or three storeys from boilers sited in lofts. I can only imagine the grief that this must have caused last winter, an what a nice little earner it would have been for out of hours callouts at premium rates to remove the ice from the drain, only to risk a repetition.