Order of Work - Moving Boiler to Attic and New Roof

berwick53

I'm in the process of buying a property that requires a new roof and a new boiler (it's getting on in age and is not condensing), with me looking at re-locating the boiler to the attic (will need a vertical flue).

The dilemma I'm having is the ordering of these two things. I messaged one of the big online-based boiler install companies, and they recommend doing the boiler work after the new roof is installed. I'm thinking of doing the opposite of what the boiler company recommends just in case the boiler installer does a bad job installing the flue.

What do you all think?

Thanks

victor2

I would have though having a brand new boiler under a roof as it is being replaced is not a wise choice. You presumably have a working boiler at the moment, so why not get the roof done first?

berwick53

Thanks, and yeah, it could be done in either order. I was thinking that if the boiler was done first the roofers would do a better job weatherproofing the flue than the boiler installer would.

Slinky

We relocated our boiler from the kitchen to a cupboard in what is my husband's office. It adjoins the cupboard which houses the hot water tank. Given the amount of heat thrown out by them both, there's no way I would want to waste that by having it in the loft. He's nice and toasty with the cupboard door open when it's running.

victor2

Slinky said:

We relocated our boiler from the kitchen to a cupboard in what is my husband's office. It adjoins the cupboard which houses the hot water tank. Given the amount of heat thrown out by them both, there's no way I would want to waste that by having it in the loft. He's nice and toasty with the cupboard door open when it's running.

Modern boilers shouldn't give out any significant heat when running, not even much through the flue. A hot water tank, especially if not well insulated, could though.

Slinky

victor2 said:

Slinky said:

We relocated our boiler from the kitchen to a cupboard in what is my husband's office. It adjoins the cupboard which houses the hot water tank. Given the amount of heat thrown out by them both, there's no way I would want to waste that by having it in the loft. He's nice and toasty with the cupboard door open when it's running.

Modern boilers shouldn't give out any significant heat when running, not even much through the flue. A hot water tank, especially if not well insulated, could though.

Well our WB does! And the tank is brand new also. Some of the heat is probably coming from the pipework.

FreeBear

victor2 said:

Slinky said:

We relocated our boiler from the kitchen to a cupboard in what is my husband's office. It adjoins the cupboard which houses the hot water tank. Given the amount of heat thrown out by them both, there's no way I would want to waste that by having it in the loft. He's nice and toasty with the cupboard door open when it's running.

Modern boilers shouldn't give out any significant heat when running, not even much through the flue. A hot water tank, especially if not well insulated, could though.

Viessmann 050W installed in June of this year, so definitely a modern boiler. Only used it a few times to heat some hot water, and it certainly does radiate some heat. How much, I can't quantify, but the temperature sensor in the hallway registers a slight rise when the boiler is running.

Having looked inside the casing, there is zero insulation, so not surprising that the casing gets warm.

Putting a boiler up in the loft will require some very long runs of pipework - If it is a combi, you'll need to run the tap longer before getting any hot water out. During the winter months, the boiler will be firing up at regular intervals as the frost protection kicks in (wasting gas and heat). You'll also need to board out the area surrounding the boiler as well as a wide path from the loft hatch. If you don't have the loft boarded, most Gas Safe engineers will refuse to go near it for servicing/repairs.

If you are planning on fitting a combi boiler, think about where you use the most hot water, and site the boiler close by. Most people have the boiler in the kitchen for that reason. Although, in a bungalow, distance from taps isn't such a big problem. I had my boiler installed in the hallway below the bathroom - A compromise as running gas to the back of the house would have been a major problem..

If you do decide to put the boiler in the loft, get the roof done first, but have the boiler installed before the scaffolding is removed.

Belenus

berwick53 said:

Thanks, and yeah, it could be done in either order. I was thinking that if the boiler was done first the roofers would do a better job weatherproofing the flue than the boiler installer would.

Not necessarily.

Boiler installers probably fit far more flues in roofs than do roofers so, in my opinion, are just as likely if not more likely to do a decent job.

We recently had a new boiler installed. The installers removed the existing roof flue and fitted a new flue in a different position.

As far as we can tell they did a first class job.

GDB2222

Can you perhaps get the boiler man to talk to the roofer?

FreeBear

victor2 said:

Slinky said:

We relocated our boiler from the kitchen to a cupboard in what is my husband's office. It adjoins the cupboard which houses the hot water tank. Given the amount of heat thrown out by them both, there's no way I would want to waste that by having it in the loft. He's nice and toasty with the cupboard door open when it's running.

Modern boilers shouldn't give out any significant heat when running, not even much through the flue. A hot water tank, especially if not well insulated, could though.

Just come across an interesting paper on boiler efficiency where casing heat loss is quantified - https://www.researchgate.net/publication/276926502_ANALYSIS_OF_THE_ENERGY_AND_COST_SAVINGS_CAUSED_BY_USING_CONDENSING_BOILERS_FOR_HEATING_DWELLINGS_IN_GREECE - Table 1 on page 2 gives a range of 1.4% to 2.1%. For a 30KW boiler, that equates to 420W to 630W at full power. Most boilers should be modulating down, so the casing heat loss won't be as great. But when you are trying to maximise your heating efficiency, every little bit helps.

victor2

FreeBear said:

victor2 said:

Slinky said:

We relocated our boiler from the kitchen to a cupboard in what is my husband's office. It adjoins the cupboard which houses the hot water tank. Given the amount of heat thrown out by them both, there's no way I would want to waste that by having it in the loft. He's nice and toasty with the cupboard door open when it's running.

Modern boilers shouldn't give out any significant heat when running, not even much through the flue. A hot water tank, especially if not well insulated, could though.

Just come across an interesting paper on boiler efficiency where casing heat loss is quantified - https://www.researchgate.net/publication/276926502_ANALYSIS_OF_THE_ENERGY_AND_COST_SAVINGS_CAUSED_BY_USING_CONDENSING_BOILERS_FOR_HEATING_DWELLINGS_IN_GREECE - Table 1 on page 2 gives a range of 1.4% to 2.1%. For a 30KW boiler, that equates to 420W to 630W at full power. Most boilers should be modulating down, so the casing heat loss won't be as great. But when you are trying to maximise your heating efficiency, every little bit helps.

Thanks for that. Very interesting - I suppose it isn't worth a manufacturer investing in making the heat exchanger even more efficient for the relatively small reduction in running costs.