Should a boiler outhouse be cavity walled?

[Deansplit]

Hi

I am having an extension built and a new Grant oiled fired boiler installed. I was going to have a single block 1500mm sq utility type room built to house it plus a wash mach & tumble dryer (a tight fit but v limited for space). Someone said the out house should be insulated as boiler's are not really meant to be exposed to the cold. I thought people put them in garages? Can anyone advise?

 

[ianniann]

Depends what you mean by cold. Modern boilers typically include frost protection so that they will fire up if it gets too cold. Obviously you don't want this to happen much but it does mean boilers are safe enough almost anywhere.

The main issue you need to worry about is heat loss. The boiler itself, a new one anyway, isn't going to lose massive amounts of heat but all that hot pipework is like having a radiator in your "almost outside" blockhouse. Very wasteful, very expensive, and not so clever when you're trying to have a shower from a pipe that starts out by heating your boiler house. So insulate all that pipework. Since it is going to be a utility room rather than an unused boiler house I'd build it with an insulated cavity wall so it will be a little warmer, and that will help the pipes to stay warm while they make their way into your home.

 

[MIGEM]

Some oil fired boilers can be stored outside and are designed to be, so it depends on your particular model.
Boilers can be installed in outhouses, and in lofts, but pipe work should be insulated and the boiler should be protected with a frost stat.
I would imagine that building control, or maybe planning approval was obtained? The ceiling will be insulated and the external door, if there is one, will not be a draughty wooden door.
Cant see a problem.

 

[Deansplit]

Thx guys - it's a Grant boiler ... and we're in Northern Ireland on the sea front so it gets cold!! Mmmm, I'm so ridiculously tight for space tho - what if I keep it single block but dry line so use much less thickness than cavity? It'll have a double glazed door and I can insulate the roof to the max.

I actually posted another thread re: where to put the manifolds for an UFH system - I had planned to put these in the same boiler hse but maybe they should be inside the home for the same reason?

 

[MIGEM]

Make sure your tumble dryer is externally ducted too. A hot boiler full of combustable fluff could ruin your dream, and humidity in the outhouse would also be absorbed by the lint/fluff sitting in the boiler casing.

 

[Deansplit]

Oh, didn't even think bout that, thx for letting me konw - so as long as it's ducted well, it's ok to do, right?

 

[MIGEM]

Oh, didn't even think bout that, thx for letting me konw - so as long as it's ducted well, it's ok to do, right?

Cant see why not. Check the boiler installation instructions too, for minimum distances for operation, access and for servicing of the boiler, and for vent exhaust positions in relation to the boiler flue terminal.

 

[PEDANTICVINDICTIVEMAN]

Wont building regs and the Officer demand that the walls are of a cetain U value heat loss wise anyway if it's new

 

[mointainwalker]

UFH manifolds:

If sited in the outhouse that means every circuit is going to have to run out there. This may well give you problems with pipe-runs, lengths, crossing-over etc. That apart I found it much easier for circuit-planning to have the manifold central (ish) and run one central feed-pipe to it.

Also less heat -loss from one 20 mm feed-pipe in the outhouse than three or four 16 mm circuit-pipes going out in the cold.

 

[Deansplit]

The out house is just outside the kitchen (only room which will have UFH) - but I think I'll situate it inside a cupboard to combat the heat loss issue.

 

[SteNova]

my oil one is in an outhouse, along with fridge, freezer, washer and dryer, single brick, insulated roof, we never had any issues with cold even when it was -16 outside, all the pipes are insluated with round stuff then boxed in with more loft insluation packed round them

 

[Agile]

The boiler room is not a "habitable room" so does not need full wall insulation.

I suggest a single rendered block and then 50mm of fire retardent wall insulation.

Tony

 

[vulcancontinental]

Depends what you mean by cold. Modern boilers typically include frost protection so that they will fire up if it gets too cold. Obviously you don't want this to happen much but it does mean boilers are safe enough almost anywhere.

The main issue you need to worry about is heat loss.

I beg to add something and I'm not familiar with the Grant boiler.

The advice above is sound but reliance on a frost stat, especially in a rural area which can be subject to power outages is not a all encompassing safety net.

No power = no frost protection and lots of water sitting in metal in a cold unheated space. Seen it - mopped it up.

You can protect the heating installation with a suitable anti-freeze and should (and double dose the inhibitor while you're at it).

What you must be aware of is that the anti-freeze will not protect any domestic hot or cold pipework so insulating this properly is really important.

See a lot of combi's in unheated spaces in rural areas that rely on a frost stat alone with minimal and less than minimal insulation on the hot and cold. Trouble waiting to happen.

If you fall into this category, go low tech solution; paraffin heater or something to use in the outhouse in extremis.

 

[Boilerman2]

Don't forget to order your grant boiler with a SHORT balanced Flue, as the standard one is for cavity wall and will be too long (they can't be cut short)

 

[Deansplit]

Oh not sure what I have - thx - I actually imagined it'd exit via the roof, obviously not an option then?