Fitting A Standard Morco Twin Walled Flue (Part 2)

[alan_fincher]

Thanks for all advice on cutting hole in roof, but the question now arises "how big a hole do I need ?"

I'm using the twin wall flue available at chandlers, and the standard roof outlet to go on top.

I could either make a hole of the smaller size of the flue pipe itself, and stop the outer pipe of the twin wall flue just short of the roof.

 

Or I could cut a hole the size of the outer pipe, and pass the whole lot through, so that the outer wall ends just above the roof line. The external part that fits to the roof seems to allow this, as it has a stepped ring near its base.

 

The instructions don't cover this at all, but the second solution seems better to me, as it explicitly keeps the inner pipe out of contact from the cut hole, and hence means if it gets very hot, it is less likely to be trying to heat the roof as well.

The only worry in my head, is that whilst I can cut a small hole to be bigger, I can't cut a big hole to be smaller - so have I missed something obvious,particularly as somebody has already told me you don't need to take both pipes through!

 

So for anyone who has done this, did you pass both walls of the flue through, or only cut a hole small enough for the inner one, please ?

[MtB]

I'd expect to cut a hole big enough for both pipes.

 

But from memory the outer flue terminal kit is not Morco branded and doesn't fit accurately or properly to the inner. All a bit Heath Robinson really, and would not be considered acceptable were they installed in houses.

[alan_fincher]

I'd expect to cut a hole big enough for both pipes.

 

But from memory the outer flue terminal kit is not Morco branded and doesn't fit accurately or properly to the inner. All a bit Heath Robinson really, and would not be considered acceptable were they installed in houses.

 

More bizarre to my untrained brain is that the inner flue fits, (and not particularly well!) inside the collar on the top of the Morco, rather than over it. It seems far more likely to me that this will result in at least some of the combustion gasses ending up outside the inner flue, rather than passing through it. But as the whole "hood" arrangement at the top is fairly open anyway, I assume that "good fit" doesn't really enter in to it - more a hope that you create enough of a "draw" that the vast majority of the combustion products get sucked up the chimney

Pictures of relevant parts.......

 

 

Edited August 18, 2015 by alan_fincher

[MtB]

 

 

"More bizarre to my untrained brain is that the inner flue fits, (and not particularly well!) inside the collar on the top of the Morco, rather than over it. It seems far more likely to me that this will result in at least some of the combustion gasses ending up outside the inner flue, rather than passing through it. But as the whole "hood" arrangement at the top is fairly open anyway, I assume that "good fit" doesn't really enter in to it - more a hope that you create enough of a "draw" that the vast majority of the combustion products get sucked up the chimney"

 

 

 

It isn't 'fairly open', it's fully open!

 

You are looking at an arrangement called a 'draught diverter'. This is necessary as a wide spectrum of flue lengths might be fitted an long flues draw harder. Varying strengths of draw would result in varying amounts of combustion air being drawn over the burners which is a Bad Thing, so needs to be prevented.

 

The open gaps each side below where the flue connects are there to decouple the flue draw from the heat exchanger draw, and it is critically important that fresh air is drawn IN though those gaps when the Morco is alight, not flue gas coming OUT. Testing for this with a smoke pen or incense stick to visually prove airflow direction is called the 'spillage test'. Basically, the incense smoke must be seen to be drawn in though the draft diverter.

 

Your concern about the inner flue resting inside the collar isn't relevant as that bit of the flue is under negative pressure. If flue gas is leaking out of it, a far larger volume of flue gas will also be spilling from the draft diverter.

 

 

(Edit as bizarrely I can't make your post appear as a conventional quote!)

Edited August 18, 2015 by Mike the Boilerman

[MoominPapa]

The open gaps each side below where the flue connects are there to decouple the flue draw from the heat exchanger draw, and it is critically important that fresh air is drawn IN though those gaps when the Morco is alight, not flue gas coming OUT. Testing for this with a smoke pen or incense stick to visually prove airflow direction is called the 'spillage test'. Basically, the incense smoke must be seen to be drawn in though the draft diverter.

Mike, is that the component which has a thermostatic switch fitted to it, which in series with the thermocouple and gas solenoid? Presumably if flue gas flows OUT, the switch trips and cuts the gas?

 

MP.

[MtB]

Mike, is that the component which has a thermostatic switch fitted to it, which in series with the thermocouple and gas solenoid? Presumably if flue gas flows OUT, the switch trips and cuts the gas?

 

MP.

 

 

Yep, that's it. That thermostat is a 'spillage detector' and turns the gas off to the pilot and main burner if it gets hot.

 

Quite a coarse and insensitive device, but better than none.

[Tecky-Talk]

Hi ...

 

As a marine GSR installer, I'd like to point out that the responses so far have failed to mention the need for an essential flue component for the MORCO - an adapter collar that sits on top of the draught diverter and provides a correctly dimensioned fit for the inner flue pipe (see image below).

 

 

If you are using a 'universal' flue - ie: one with an aluminium inner and a white enamelled outer, the inner (hot) tube goes up inside roof mounted terminal (tight fit) - see images below:

 

 

 

Note that the white enamelled tube is simply there to ensure the inner (hot) flue tube DOES NOT come into contact withe the cabin roof lining of the craft. This outer tube need to be trimmed to about 20mm above the external roof line - if it's longer the roof terminal shroud will not fit over it. The inner tube should be trimmed to the same length as the roof terminal shroud (see picture).

 

If you have followed me so far there's one more REALLY important issue to address - the flue pipe MUST BE VERTICAL ! If your roof is heavily cambered, the skirt on the roof terminal shroud cannot be massaged to fit - you must have an adaptor collar manufactured (see picture below) to ensure the flue is VERTICAL - if it isn't, the inner tube wont sit squarely on the heater's draught diverter and flue gasses WILL leak out into the gap between the inner and outer tubes - the flue will not operate efficiently and you may be at risk from CO poisoning ...

 

 

 

If you are fitting a flue to a MORCO, please seek the help of a competent (registered) installer.

 

PS: If you are a live aboard, your boat is in-scope of UK Gas Regulations. If you are not Gas Safe Registered, you CANNOT do ANY LPG work on your craft. So, if you are contemplating fitting a 'standard' MORCO IWH to your boat (ie not replacing one that has died) such an installation is ILLEGAL and you won't find a GSR installer willing to do the work. If it is a new fit on your boat, the IWH MUST have a balanced flue (ie: a room-sealed appliance which draws its combustion air from outside NOT from the cabin). The ONLY boat compatible appliance is the MORCO F11 (which needs 240v to power the flue fan).

[MtB]

Welcome to the forum Tecky Talk,

 

 

PS: If you are a live aboard, your boat is in-scope of UK Gas Regulations. If you are not Gas Safe Registered, you CANNOT do ANY LPG work on your craft. So, if you are contemplating fitting a 'standard' MORCO IWH to your boat (ie not replacing one that has died) such an installation is ILLEGAL and you won't find a GSR installer willing to do the work. If it is a new fit on your boat, the IWH MUST have a balanced flue (ie: a room-sealed appliance which draws its combustion air from outside NOT from the cabin). The ONLY boat compatible appliance is the MORCO F11 (which needs 240v to power the flue fan).

 

 

I'm intrigued now. In what way is a Morco IWH "ILLEGAL" on a boat falling within the scope of the GSIUR, exactly, please?

 

Can you quote the regulation(s) it would contravene?

 

Many thanks.

[Tecky-Talk]

(L56 Reg 30)

 

To be sure we're both on the 'same page', I'm not saying a MORCO on an in-scope boat is illegal, I'm saying tha you can't install a non-balanced flue IWH on a boat that is live-aboard (and has never had an IWH previously fitted).

 

If the subject of this thread relates to the replacement / re-siting of an existing IWH (regardless of make), a non balanced flue IWH can be fitted providing the replacement is like-for-like - ie : RINNAI REU - 85E out dictates replacement by a RINNAI REU-85E ...

[MtB]

(L56 Reg 30)

 

To be sure we're both on the 'same page', I'm not saying a MORCO on an in-scope boat is illegal, I'm saying tha you can't install a non-balanced flue IWH on a boat that is live-aboard (and has never had an IWH previously fitted).

 

Reg 30:

 

30. - (1) No person shall install a gas appliance in a room used or intended to be used as a bathroom or a shower room unless it is a room-sealed appliance.

(2) No person shall install a gas fire, other gas space heater or a gas water heater of more than 14 kilowatt gross heat input in a room used or intended to be used as sleeping accommodation unless the appliance is a room-sealed appliance.

(3) No person shall install a gas fire, other gas space heater or a gas water heater of 14 kilowatt gross heat input or less in a room used or intended to be used as sleeping accommodation and no person shall install an instantaneous water heater unless (in each case)

(a) it is a room-sealed appliance; or

( it incorporates a safety control designed to shut down the appliance before there is a build up of a dangerous quantity of the products of combustion in the room concerned.

(4) The references in paragraphs (1) to (3) to a room used or intended to be used for the purpose therein referred to includes a reference to

(a) a cupboard or compartment within such a room; or

( a cupboard, compartment or space adjacent to such a room if there is an air vent from the cupboard, compartment or space into such a room.

 

 

 

No mention of open flue water heaters being banned in a boat.

 

I hold that you CAN install an open flue Morco in a liveaboard boat, just not in a shower or bathroom or bedroom.

 

 

 

(Edit to add in the whole of reg 30.)

Edited August 19, 2015 by Mike the Boilerman

[Tecky-Talk]

[Tecky-Talk]

Mike ...

 

On the understanding that you are CCLP1B qualified, possess (cuurent) copies of BS EN ISO 10239 and PD 5482-3 (and install to them), you'll understand that these documents provide clear guidance on the requirements for IWH installation aboard small craft (both new intallations and 'like-for-like' replacements) in a manner that supplements the baseline requirements of L56...

[MtB]

Mike ...

 

On the understanding that you are CCLP1B qualified, possess (cuurent) copies of BS EN ISO 10239 and PD 5482-3 (and install to them), you'll understand that these documents provide clear guidance on the requirements for IWH installation aboard small craft (both new intallations and 'like-for-like' replacements) in a manner that supplements the baseline requirements of L56...

 

 

"Guidance", you say...

 

You initially stated "illegal".

 

C'mon now, which is it?

[alan_fincher]

Hi ...

 

As a marine GSR installer, I'd like to point out that the responses so far have failed to mention the need for an essential flue component for the MORCO - an adapter collar that sits on top of the draught diverter and provides a correctly dimensioned fit for the inner flue pipe (see image below).

 

 

None of your images will display for me, so it's hard to know exactly what you are referring to.

 

The only flue adapters i'm aware of for the Morco are the ones that relate to swapping D51 and D61 models that I seem to recall have different sized collars.

 

I have used the twin walled flue I posted an image of, and the inner flue sits inside the collar on the hood of the Morco.

 

Mike the Boilerman seemed to imply this was quite normal, so can you please explain why you belive it is not acceptable.

[MtB]

 

None of your images will display for me, so it's hard to know exactly what you are referring to.

 

The only flue adapters i'm aware of for the Morco are the ones that relate to swapping D51 and D61 models that I seem to recall have different sized collars.

 

I have used the twin walled flue I posted an image of, and the inner flue sits inside the collar on the hood of the Morco.

 

Mike the Boilerman seemed to imply this was quite normal, so can you please explain why you belive it is not acceptable.

 

 

 

'Seeming to imply' is about as far as I'd want to go!

 

I've only ever fitted three or four (the last one being perhaps ten years ago) and on each occasion I was startled by how badly made and poorly fitting all the flue components were. ISTR calling Morco for advice at the time and asking them if they supply a flue system designed to fit their product and being told they didn't, and I could use any of of the unbranded third party flues sold by chandlers.

 

Pretty unsatisfactory in my opinion. Or has this changed now? Is your flue kit 'Morco' branded Alan? And what do the installation instructions say that came with the flue say? ISTR the flues came with no fitting instructions last time I fitted one. I had to make it up as I went along. As I said earlier, totally unacceptable in a household arena these days, but these Morcos are from a preceding era.

[MtB]

If you have followed me so far there's one more REALLY important issue to address - the flue pipe MUST BE VERTICAL ! If your roof is heavily cambered, the skirt on the roof terminal shroud cannot be massaged to fit - you must have an adaptor collar manufactured (see picture below) to ensure the flue is VERTICAL - if it isn't, the inner tube wont sit squarely on the heater's draught diverter and flue gasses WILL leak out into the gap between the inner and outer tubes - the flue will not operate efficiently and you may be at risk from CO poisoning ...

 

 

I think this is unnecessarily hysterical. Where do you get this idea from? the MI don't say the flue must be accurately vertical AFAICR, although I haven't checked.

 

Provided the flue is installed in such a way that it isn't leaking there is no risk of CO due to it not being accurately vertical. As Alan points out it's an open flue appliance and the draft diverter ports are right there, wide open to atmosphere just a few millimetres away from the joint you mention.

 

This appliance is designed for fitting in boats and caravans which by their very nature move around and tilt, meaning the flue will not be vertical at all times.

P.S. the gas bod who installed the Morco for me in Reginald just bent that large aluminium roof collar to account for the roof curve and make the flue vertical IIRC. It doesn't leak and it passed a BSS recently. But I'll have a closer look at it next time I'm on the boat!

[bizzard]

The last Morco I fitted I bought the Morco flue fitting kit from (Camping and General) Canvey Island. It fitted well.

[alan_fincher]

I've only ever fitted three or four (the last one being perhaps ten years ago) and on each occasion I was startled by how badly made and poorly fitting all the flue components were. ISTR calling Morco for advice at the time and asking them if they supply a flue system designed to fit their product and being told they didn't, and I could use any of of the unbranded third party flues sold by chandlers.

 

Pretty unsatisfactory in my opinion. Or has this changed now? Is your flue kit 'Morco' branded Alan? And what do the installation instructions say that came with the flue say? ISTR the flues came with no fitting instructions last time I fitted one. I had to make it up as I went along. As I said earlier, totally unacceptable in a household arena these days, but these Morcos are from a preceding era.

 

The flue pips and external flue I bought don't carry any branding or have any instructions whatsoever, and are the ones sold at Midland Chandlers, (and nmany other chandlers).

 

However checking Morcos site, they do seem to be marketed by Morco themsolves....

 

Double Walled Flue

 

External flue

 

The only questionable bit (apart from zero instructions!) is the inprecise fit of the inner flue into te collar lon the top of the D61.

Edited August 20, 2015 by alan_fincher