Combi in the loft

[VisionSet]

Okay, I've done a bit more research and it seems the Heat bank option has leapt up to a ton shy of 2K so the combi is definitely still a contender. Still looking at the actual make model options but the Worcester Bosch 40kW HE Plus Condensing Combi is a strong possibility.

Now I still want to stick this stuff in the loft. A good location for me is attached to the party wall. Are these upto supporting 50Kg?

As far as the access requirements go at present you can pop your head through the loft and it would be right in front of you, since the loft is low head room (4ft max at apex) it would be more convenient for service bod to tackle it from waste at hatch height. So hopefully just a loft ladder will do.

Other boiler options after top reliabilty/quality are satisfied may hinge on the program options. Since it will be in the loft some sort of remote option for the programmer would be best. I take it this is common. Though alot seem geared to kitchen installation, 800 high, nice finish, inbuilt digital displays - all of which are unnecessary for my loft. Suppose best place for fault diagnostic display is on boiler.

Other than that I want max flow/heat 16 l/min @35°C rise to beat!

Can I do the whole fitting or do I need a Corgi chap for final connection. How is the guarantee on the boiler affected by this? Will I EVER find a plumber willing to do JUST the hook up (twiddle, fiddle, poke, 'that's okay mate') at a reasonable rate?

Thoughts? Everyone it seems loves a boiler thread :)

[Andy Hall]

As long it's a structural , load bearing wall in good condition, that should be OK.

You have to board and light the loft and put in a guard rail, but the loft ladder is OK.

Well it's pretty simple. 40 kW gives 16 lpm at dT=35 degrees. If you want more then you will need a larger boiler. There are a few

46kW models around that will give you around 18lpm but they cost rather more - e,g, MAN Micromat 46kW combi.

This is your choice. Legally (according to Gas Safety Installation and Use Regulations 1998), you can DIY this if you are "competent". This is by exception, in the sense that there is a specific requirement (via the HSE acting as policeman) if you are installing professionally to be a member of CORGI. The legislation does not define competent with respect to DIY and doesn't positively mention DIY. CORGI membership certainly does require training but of course this is no absolute guarantee of a good job. The HSE is certainly aware that DIY gas fitting goes on and periodically there have been discussions about trying to stop it, but there is no justification for doing so from the rate of problems occuring from it, and they admit that. Plus it would be hard to enforce.

There is now a requirement with respect to the energy saving aspects of the Building Regulations Part L1. If you use a CORGI fitter to do the work, then he can self certify it. Otherwise you have to apply for a Building Notice at the local authority - cost around £100 I believe.

It's a difficult proposition to ask a CORGI fitter to come along and sprinkle holy water on your work for two reasons.

- It is not that interesting business-wise if they haven't supplied and fitted.

- They are taking responsibility for your work with respect to the gas supply and the flue. Once you have fitted them, it may be difficult to see those and many would not touch it under those circumstances

- Most have plenty of work, so have no real need to do this for you

From a competence perspective, have a look through Ed Sirett's FAQ. Ed is a CORGI fitter (as well as being a thoroughly nice guy), and his comments are valuable.

The main ones are do you have a good, repeatable result with soldering fittings together and do you understand all the issues involved before you start?

.andy

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[VisionSet]

Well it is a party loft wall, I suspect it is only there as a boundary, I doubt it is load bearing, but it is brick. and it is supported by the whole brick party partition.

the whole loft? and even if it would never be used by trades person?

lighting no problem.

What is a guard rail?

yes for sure

will do.

Yes, I have no qualms about my ability. It was just the guarantee aspect, am I likely to violate the boiler manufacturers requirements, I suspected they required a Corgi fitter. I know... I shall phone WB etc.

Cheers Andy

-- Mike W

[IMM]

Not the whole, loft adequately around the hatch, to and around the boiler. A light over the boiler and hatch and a rail around the hatch so no one will fall down it. This may be wood screwed to the rafters to make the rail.

See above.

Use Powerflux and flush properly after with Superfloc.

The law say you must be "competent". CORGI registration is only for when you make money out of fitting gas equipment. It is to stop the cowboys.

[Andrew Gabriel]

The part in the loft usually isn't though. Gable-end walls are notoriously weak, and can sometimes be blown out with a strong wind, so be careful. They don't support anything and have no weight on them (above any purlins). I certainly wouldn't mount a boiler anywhere near the top of such a wall.

[VisionSet]

mmm, this is what I feared. There are purlins and I suspect I can get it central to these. The house is well built 1930, I'll have a good look at it, get my uncle architect to take a look. Don't know what to do otherwise, substantially repoint it, though it doesn't really look like it needs it.

-- Mike W

[IMM]

What are you on about? they have the same foundations as the other walls. I have mounted boilers on gables and never had any problems. Boilers are not that heavy to worry a gable end.

[Andy Hall]

50kg mounted high up can create a substantial load.......

.andy

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[IMM]

On a wall like a gable end? Which has racking strength from the roof timbers too? Please.

[Andy Hall]

That depends on the timber structure and which way the members go.

.andy

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[IMM]

You don't know anything about construction.

[Andy Hall]

OK, Mr Cleverclogs,

So explain what happens when the roof structure is of trussed rafters with ties and there are not substantive purlins using the gable end walls.....

Is the gable end wall then as load bearing or needing to be as strong?

.andy

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[Andrew Gabriel]

In article , "IMM" writes:

Gable end is often not tied to the roof trusses at all. In any case, it's not a very solid structure, so tying it to the roof trusses does not necessarily gain a lot. Also, it doesn't have any weight on it (the roof doesn't rest on it) -- the weight is just that of the wall itself. You shouldn't think of the mortar providing any lateral strength (one hairline crack, as it will surely have, and there's no strength in that direction). So just imagine it's built of loose bricks with no mortar and decide if you think it can support sufficient sideways weight. Providing boiler's low enough that there's still many times the weight of the boiler above the mounting point and the centre of gravity remains inside the wall, you would probably be OK. If there isn't much weight above the boiler mounting points and centre of gravity when taking the boiler weight into account is not still within the wall, it's an unstable structure which could collapse eventually. In addition to the displacement of the centre of gravity, there's a question of if the wall is strong enough to carry the weight without the weight pulling out some bricks, which will depend on the condition of the mortar (which in this case provides the frictional force preventing this) and the weight of wall above the mounting. Again, failure is likely if the weight above the mounting points is not substantial, i.e if you position the boiler near the top of the wall, or if the mortar is not in good condition.

You can easily model all this with a child's building blocks.

One way round this would be to get the neighbour on the other side of the party wall to have an identical boiler fitted on their side, with single bolts going through the wall fixing up bother boilers. Then the center of gravity will remain in the middle of the wall so the structure is stable, and there's no force pulling bricks out of the wall.

[Set Square]

The trusses get in the way of installing and accessing the combi?

[Andy Hall]

I was thinking more in terms of the gable ends not being incorporated with the roof trusses at all.....

.andy

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[VisionSet]

Well it isn't a gable end - it is a party wall.

If we assume it is not up to the weight. What can I do to make it suitable?

Standard 30's construction 4ft void at apex, purlins and rafters. Brick stretcher party wall in good visual condition, lime mortar.

-- Mike W

[IMM]

As I said "You don't know anything about construction"

[IMM]

he has never seen the "ladder".

[Andy Hall]

????

.andy

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[Andy Hall]

I was asking you to explain something, so if this is your best offer of a reply, I guess that I can draw my own conclusions about your knowledge of the subject.

.andy

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