Confusion over gas water heaters

[brian1042]

Having searched through this Forum, I have found various discussions on gas water heaters, but have to admit to some confusion on my part.

 

I have got the understanding from various places that if I fitted a new gas water heater, in order to comply with BSS requirements it would have to:

1) be a sealed room type

2) have a balanced flue.

 

But ...

 

... there seems to be some dispute about what can and cannot be fitted (and even who can fit it). Maybe it is my poor understanding of what is being stated, so I am happy to be told it is all clear and I should have read things more carefully, but please give me some pointers.

 

Are the above required for BSS compliance?

 

For BSS is there a certificate or some such needed from a recognised (maybe Corgi?) fitter?

 

This is advertised currently:

http://www.force4.co.uk/722/Rinnai-Gas-Water-Heater.html

 

The firm replied to an email from me to confirm that this water heater does not meet either 1 or 2 above. If this is the case, and 1 and 2 are requirements, I wondered why they are selling it, but I guess that is their business.

 

Edit: Directly after replying to me the product has been removed, so apologies, the link does not work.

 

If this heater does not meet BSS requirements, can anyone please suggest an instant gas water heater that is around the same price that does meet BSS requirements?

 

Sorry if I have opened a can of worms with these questions.

 

Thank you.

Edited January 22, 2013 by brian1042

[RobinJ]

Having searched through this Forum, I have found various discussions on gas water heaters, but have to admit to some confusion on my part.

I have got the understanding from various places that if I fitted a new gas water heater, in order to comply with BSS requirements it would have to:

1) be a sealed room type

2) have a balanced flue.

You have to be clear what is permitted for existing boats (service/replacement) and new boats and whetehr we are talking proivately owned or hire boats.

The BSS web site has details on the code.

New boats need to comply with RCD too, and these conditions may differ from BSS.

This is advertised currently:

http://www.force4.co.uk/722/Rinnai-Gas-Water-Heater.html

The firm replied to an email from me to confirm that this water heater does not meet either 1 or 2 above. If this is the case, and 1 and 2 are requirements, I wondered why they are selling it, but I guess that is their business.

Not all boats need to comply with BSS, especiually sea going vessels, so I am not surprised a chandlery will be supplying equipment that may not be suitable for inland waters.

If this heater does not meet BSS requirements, can anyone please suggest an instant gas water heater that is around the same price that does meet BSS requirements?

Oh where is my crystal ball!

[brian1042]

Thank you for your responses, Robin.

 

You have to be clear what is permitted for existing boats (service/replacement) and new boats and whetehr we are talking proivately owned or hire boats.

 

I have an old, existing boat that I own privately.

[DeanS]

This threadmay help.

 

You need to be a competant person to install it.

You could also install it and get a gas registered person to check your installation.

 

It involves using a jigsaw to cut a hole through your boat roof, 2 screws on a wall to support the heater frame, connecting a gas supply to it, and running the cold water supply pipe to it, and the hot water pipe from it.

[brian1042]

This threadmay help.

 

You need to be a competant person to install it.

You could also install it and get a gas registered person to check your installation.

 

It involves using a jigsaw to cut a hole through your boat roof, 2 screws on a wall to support the heater frame, connecting a gas supply to it, and running the cold water supply pipe to it, and the hot water pipe from it.

 

Thank you Dean.

 

I am pretty handy, so doing it and getting some to check seems like a good idea. Where I am a bit confused on fitting is how to ensure the hot water goes both to the shower and the kitchen tap. The two are on opposite side of a corridor, and pipes can go under the floor. I currently have a calorifier and do not want to lose the use of that.

Edited January 22, 2013 by brian1042

[DeanS]

Thank you Dean.

 

I am pretty handy, so doing it and getting some to check seems like a good idea. Where I am a bit confused on fitting is how to ensure the hot water goes both to the shower and the kitchen tap. The two are on opposite side of a corridor, and pipes can go under the floor. I currently have a calorifier and do not want to lose the use of that.

 

 

You use a T-piece in the hot water pipe exiting the gas heater (Have a piece of pipe from the heater outlet...down to the floor level, along your passage...and put the t-piece when it's opposite the galley. Run a piece of pipe to your kitchen sink, and another piece to your shower. )Route the piping whichever suits you....under the floor is normally the way to go. Speedfit pipe and fittings is what I used. PsyCloud recently installed the same system.

 

To integrate it with a calofifier, you would possibly need to use valves to isolate one set of hot water supply pipes from the other....but others on this forum will be able to give more info on that...I wouldnt think it would be a good idea to have hot water from the calorifier pushing backwards into the gas heater...so you will need to fit a way of selecting either one or the other.

Edited January 22, 2013 by DeanS

[brian1042]

You use a T-piece in the hot water pipe exiting the gas heater (Have a piece of pipe from the heater outlet...down to the floor level, along your passage...and put the t-piece when it's opposite the galley. Run a piece of pipe to your kitchen sink, and another piece to your shower. )Route the piping whichever suits you....under the floor is normally the way to go. Speedfit pipe and fittings is what I used. PsyCloud recently installed the same system.

 

To integrate it with a calofifier, you would possibly need to use valves to isolate one set of hot water supply pipes from the other....but others on this forum will be able to give more info on that...I wouldnt think it would be a good idea to have hot water from the calorifier pushing backwards into the gas heater...so you will need to fit a way of selecting either one or the other.

 

Thanks again! If anyone has a solution to being able to switch back and forth betwen the gas heater and the calorifier, it would be greatly appreciated.

Edited January 22, 2013 by brian1042

[RickH]

I'm very interested in what you come up with as I may well do the same , the Eberspacher is just an expensive anchor !

[Tony Brooks]

Thanks again! If anyone has a solution to being able to switch back and forth betwen the gas heater and the calorifier, it would be greatly appreciated.

 

 

The usual problem with combining both a calorifier and instant gas heater is that if hot water from the calorifier is fed to the gas heater the water would boil - not much good if you are showering or have your hands under it. I think the BSS might have something to say about this.

 

You could simply T the hot from the heater into your existing hot water pipe and let the original pipework distribute the hot water but if you do this I suspect the restrictor in the gas water heater will cause the majority of the flow to come from the calorifier and if that is cold you are still no better off.

 

I think the easiest thing to do would be to use a 3 port T valve to make the T connection. If you put it in a convenient place and peg/block the handle so you can not put the handle in the position that aligns the ports as a T then by simply turning the valve through 180 degrees you can select the hot supply from either the calorifier or the gas heater only.

[bizzard]

Instantaneous gas hot water heaters are brilliant. Folk seem to be seeing some sense at last as they appear to be making a come back, they are the cheapest ''apart from landline mains immersion heater perhaps'', and the quickest way to heat water. But you must drain them when the boats unoccupied in the winter as they can freeze up easily and bust.

[brian1042]

The usual problem with combining both a calorifier and instant gas heater is that if hot water from the calorifier is fed to the gas heater the water would boil - not much good if you are showering or have your hands under it. I think the BSS might have something to say about this.

 

You could simply T the hot from the heater into your existing hot water pipe and let the original pipework distribute the hot water but if you do this I suspect the restrictor in the gas water heater will cause the majority of the flow to come from the calorifier and if that is cold you are still no better off.

 

I think the easiest thing to do would be to use a 3 port T valve to make the T connection. If you put it in a convenient place and peg/block the handle so you can not put the handle in the position that aligns the ports as a T then by simply turning the valve through 180 degrees you can select the hot supply from either the calorifier or the gas heater only.

 

Excellent! Thank you!

 

Instantaneous gas hot water heaters are brilliant. Folk seem to be seeing some sense at last as they appear to be making a come back, they are the cheapest ''apart from landline mains immersion heater perhaps'', and the quickest way to heat water. But you must drain them when the boats unoccupied in the winter as they can freeze up easily and bust.

 

Thanks for that. Very helpful.

[brian1042]

Thank you for all the helpful replies.

 

Would anyone be willing to stick their neck out and tell me if this will comply with BSS requirements please?

http://www.force4.co...ter-Heater.html

 

It is not a sealed room type.

 

It does not have a balanced flue.

 

Having looked at the BSS site, I am now of a view that it does comply, but I am inexperienced in this area and would not want to purchase something that will have to be removed.

 

Thanks.

Edited January 22, 2013 by brian1042

[Bobbybass]

You have to be clear what is permitted for existing boats (service/replacement) and new boats and whetehr we are talking proivately owned or hire boats.

The BSS web site has details on the code.

New boats need to comply with RCD too, and these conditions may differ from BSS.

 

Not all boats need to comply with BSS, especiually sea going vessels, so I am not surprised a chandlery will be supplying equipment that may not be suitable for inland waters.

 

Oh where is my crystal ball!

 

 

If you had only known...you could have bought mine !!!

 

http://www.ebay.co.uk/itm/140905808919?ssPageName=STRK:MESOX:IT&_trksid=p3984.m1559.l2649

[Teadaemon]

There's a number of points that bear discussion.

 

1) Do you live on the boat? If you do, then the gas installation comes under GSIUR and you need to get a Gas Safe registered person to work on it.

 

1a) Whilst non room sealed instantaneous water heaters aren't prohibited by the BSS, GSIUR has a fair bit to say about them (I don't know exactly what as I'm not Gas Safe registered). You may find it tricky to get a Gas Safe registered person who is prepared to fit one, or they may only fit one in certain places on the boat.

 

2) If you do fit one, then you'll need to make sure that the ventilation on the boat is sufficient - the formula is in appendix K of the 2013 checking procedures (available here).

 

3) A room sealed (aka balanced flue) heater will not require any additional ventilation, as it draws it's combustion air from outside the boat.

 

Personally, if I were going to fit a gas instantaneous water heater on a boat, I'd fit a room sealed one.

 

Edited to add: I can't get the link posted above to work, but one other point to remember is that whatever unit you fit must have a flame failure device (check 8.7.1).

 

As far as plumbing it into a hot water system with a calorifier, would it be possible to use a one way valve on the output from the water heater, to prevent hot water being pushed back into the heat exchanger? I can't think of a good reason why it couldn't, but somebody with a more extensive knowledge of plumbing may know something I don't.

Edited January 22, 2013 by Teadaemon

[Tony Brooks]

There's a number of points that bear discussion.

 

1) Do you live on the boat? If you do, then the gas installation comes under GSIUR and you need to get a Gas Safe registered person to work on it.

 

1a) Whilst non room sealed instantaneous water heaters aren't prohibited by the BSS, GSIUR has a fair bit to say about them (I don't know exactly what as I'm not Gas Safe registered). You may find it tricky to get a Gas Safe registered person who is prepared to fit one, or they may only fit one in certain places on the boat.

 

2) If you do fit one, then you'll need to make sure that the ventilation on the boat is sufficient - the formula is in appendix K of the 2013 checking procedures (available here).

 

3) A room sealed (aka balanced flue) heater will not require any additional ventilation, as it draws it's combustion air from outside the boat.

 

Personally, if I were going to fit a gas instantaneous water heater on a boat, I'd fit a room sealed one.

 

As far as plumbing it into a hot water system with a calorifier, would it be possible to use a one way valve on the output from the water heater, to prevent hot water being pushed back into the heat exchanger? I can't think of a good reason why it couldn't, but somebody with a more extensive knowledge of plumbing may know something I don't.

 

 

Not likley to happen because the pressure would be similar on both sides of it if anything started to "push back". The problem is (as IO see it) preventing a cold calorifier feeding the hot outlets because of the restriction in the gas heater. I also think back pressure into the diaphragm chamber would close the gas valve. Hence my advice about a 3 way T valve.

[Bobbybass]

 

As far as plumbing it into a hot water system with a calorifier, would it be possible to use a one way valve on the output from the water heater, to prevent hot water being pushed back into the heat exchanger? I can't think of a good reason why it couldn't, but somebody with a more extensive knowledge of plumbing may know something I don't.

 

I was pondering this...?

 

As the gas heater..and calorifier....would be running from the same pressurized water pump...and thus they would both have equal input pressure...if you turned on a hot tap..how would it know to take the hot water either from your gas heater...or the calorifier.(which may be cold)...?

Maybe..I'm being dumb..?

Wouldn't you need a manual diverter tap..?

 

Not likley to happen because the pressure would be similar on both sides of it if anything started to "push back". The problem is (as IO see it) preventing a cold calorifier feeding the hot outlets because of the restriction in the gas heater. I also think back pressure into the diaphragm chamber would close the gas valve. Hence my advice about a 3 way T valve.

You beat me to it....

[alan_fincher]

I think the easiest thing to do would be to use a 3 port T valve to make the T connection. If you put it in a convenient place and peg/block the handle so you can not put the handle in the position that aligns the ports as a T then by simply turning the valve through 180 degrees you can select the hot supply from either the calorifier or the gas heater only.

Almost, but not quite......

 

Assuming I have my valve "terminology" correct, you need an L-port valve, rather than a T-port one, I think.

 

That is one with three ports, where one port is connected to each of the other two in turn on an "either/or, but never both" arrangement, depending on which way the lever is set.

 

Feed the hot water output from your Morco into one of those selectable ports, and the hot water output from your calorifier to the other. Then use the port which can be directed at either of them to connect to all your hot water taps.

 

With the lever in the "Morco" position, it is the same as the Morco directly connected to the taps, and the calorier feed simply sees a dead end at the valve - no different from in a normal installation, when all taps are turned off. Lever in the "calorifier" position, and the situation is reversed. It doesn't matter if the Morco still has its pilot on, because it "sees" nothing different from what it would do in a normal installation when all taps are turned of.

 

It's how we did ours, and it works a treat, although ninety something percent of the time it is on "calorifier", and if it is, we would have the pilot on the Morco turned off, so as not to waste gas needlessly.

[brian1042]

There's a number of points that bear discussion.

 

1) Do you live on the boat? If you do, then the gas installation comes under GSIUR and you need to get a Gas Safe registered person to work on it.

 

1a) Whilst non room sealed instantaneous water heaters aren't prohibited by the BSS, GSIUR has a fair bit to say about them (I don't know exactly what as I'm not Gas Safe registered). You may find it tricky to get a Gas Safe registered person who is prepared to fit one, or they may only fit one in certain places on the boat.

 

2) If you do fit one, then you'll need to make sure that the ventilation on the boat is sufficient - the formula is in appendix K of the 2013 checking procedures (available here).

 

3) A room sealed (aka balanced flue) heater will not require any additional ventilation, as it draws it's combustion air from outside the boat.

 

Personally, if I were going to fit a gas instantaneous water heater on a boat, I'd fit a room sealed one.

 

Edited to add: I can't get the link posted above to work, but one other point to remember is that whatever unit you fit must have a flame failure device (check 8.7.1).

 

As far as plumbing it into a hot water system with a calorifier, would it be possible to use a one way valve on the output from the water heater, to prevent hot water being pushed back into the heat exchanger? I can't think of a good reason why it couldn't, but somebody with a more extensive knowledge of plumbing may know something I don't.

 

Thank you for a very comprehensive reply.

[Tony Brooks]

Almost, but not quite......

 

Assuming I have my valve "terminology" correct, you need an L-port valve, rather than a T-port one, I think.

 

That is one with three ports, where one port is connected to each of the other two in turn on an "either/or, but never both" arrangement, depending on which way the lever is set.

 

Feed the hot water output from your Morco into one of those selectable ports, and the hot water output from your calorifier to the other. Then use the port which can be directed at either of them to connect to all your hot water taps.

 

With the lever in the "Morco" position, it is the same as the Morco directly connected to the taps, and the calorier feed simply sees a dead end at the valve - no different from in a normal installation, when all taps are turned off. Lever in the "calorifier" position, and the situation is reversed. It doesn't matter if the Morco still has its pilot on, because it "sees" nothing different from what it would do in a normal installation when all taps are turned of.

 

It's how we did ours, and it works a treat, although ninety something percent of the time it is on "calorifier", and if it is, we would have the pilot on the Morco turned off, so as not to waste gas needlessly.

 

 

Either will do the job as long as you block the handle on the T port to prevent it forming a simple T connection.

Edited January 22, 2013 by Tony Brooks

[alan_fincher]

Either will do the job as long as you block the handle on the T port to prevent it forming a simple T connection.

Fair enough, but with the L-Port you don't need to.

 

Personally, if I were going to fit a gas instantaneous water heater on a boat, I'd fit a room sealed one.

The problem being of course that, as has been repeatedly discussed on here, no room sealed one is available that is a sensible fit for a narrow boat, the external flues being an essential part of them, and completely inconsistent with actually wanting to take the boat under typical bridges or tunnels.

 

I have yet to hear of anyone getting around this problem, given that modifying the flue, or designing an alternate one would undoubtedly not be a good idea.

 

So though it might sound like a good idea, there is a very good reason why nobody does.

[MtB]

Good post from Teadaemon.

 

 

1a) Whilst non room sealed instantaneous water heaters aren't prohibited by the BSS, GSIUR has a fair bit to say about them (I don't know exactly what as I'm not Gas Safe registered). You may find it tricky to get a Gas Safe registered person who is prepared to fit one, or they may only fit one in certain places on the boat.

 

To expand on this:

 

1) The GSIUR broadly speaking prohibits open flue water heaters from being fitted in sleeping areas or in rooms containing a bath or shower.

 

2) One Gas Safe Bod is not the same as another. You'll need a Gas Safe bod who has three separate tickets: Boiler and water heaters, LPG, and gas in boats. I can't remember the ticket numbers but ask to see his Gas Safe ID card. We all carry them and it lists the categories each technician is qualified to work on.

 

3) Most Gas Safe bods will refuse to fit an open flue water heater on a boat because either they don't hold the correct tickets and don't want to fess up, or they are unfamiliar with the regs and scared of getting hauled over the coals by GSR if they get it wrong. Or both.

 

MtB

 

(Speeling edit.)

 

I have yet to hear of anyone getting around this problem, given that modifying the flue, or designing an alternate one would undoubtedly not be a good idea.

 

Modifying a flue on a room sealed appliance is an offence under the GSIUR Alan, just so you know. We are not allowed to modify a gas appliance in any way that might alter it from the specification that was tested for CE approval.

 

Not that the GSIUR apply to leisure boats. But they DO apply to liveaboards (and hire boats, I think).

 

MtB

Edited January 22, 2013 by Mike the Boilerman

[smileypete]

Something to bear in mind is that instant gas water heaters don't get on with thermostatic mixers, and prefer a manual mixer. Also a thermostatic mixer is almost essential with a calorifier.

 

So maybe have one of each type in the shower, and tee their outlets together before the shower outlet elbow.

 

That way it's easy to switch over when calorifer water runs out, also use a little tepid calorifier water to improve the 'showering experience' of the gas water heater in winter.

 

cheers, Pete.

~smpt~

[brian1042]

I'm very interested in what you come up with as I may well do the same , the Eberspacher is just an expensive anchor !

 

Not sure what the connection is with the Eberspacher ... ?

 

Something to bear in mind is that instant gas water heaters don't get on with thermostatic mixers, and prefer a manual mixer. Also a thermostatic mixer is almost essential with a calorifier.

 

So maybe have one of each type in the shower, and tee their outlets together before the shower outlet elbow.

 

That way it's easy to switch over when calorifer water runs out, also use a little tepid calorifier water to improve the 'showering experience' of the gas water heater in winter.

 

cheers, Pete.

~smpt~

 

Thank you Pete. I have a lot of info to take in. Out of interest, what if I just didn't bother with the calorifier? My thinking is I would still have to cap it somehow, so I might as well use the heat of the engine when it is running.

[brian1042]

Good post from Teadaemon.

 

 

 

 

To expand on this:

 

1) The GSIUR broadly speaking prohibits open flue water heaters from being fitted in sleeping areas or in rooms containing a bath or shower.

 

2) One Gas Safe Bod is not the same as another. You'll need a Gas Safe bod who has three separate tickets: Boiler and water heaters, LPG, and gas in boats. I can't remember the ticket numbers but ask to see his Gas Safe ID card. We all carry them and it lists the categories each technician is qualified to work on.

 

3) Most Gas Safe bods will refuse to fit an open flue water heater on a boat because either they don't hold the correct tickets and don't want to fess up, or they are unfamiliar with the regs and scared of getting hauled over the coals by GSR if they get it wrong. Or both.

 

MtB

 

(Speeling edit.)

 

 

 

Modifying a flue on a room sealed appliance is an offence under the GSIUR Alan, just so you know. We are not allowed to modify a gas appliance in any way that might alter it from the specification that was tested for CE approval.

 

Not that the GSIUR apply to leisure boats. But they DO apply to liveaboards (and hire boats, I think).

 

MtB

 

Thank you Mike.

[Teadaemon]

To get around the flue problem, I have found this, but it has a whole lot of other issues regarding fitting (especially if it's a retro-fit), and I know from friends who have the blown air heaters that Propex kit isn't cheap. I'd also want it confirmed in writing that it has a flame failure device, as it isn't obvious from the write up (but I suspect that it does as they specifically mention installation on inland waterways vessels).

 

I'd add that in addition to being prohibited by GSIUR, modifying a flue would also cause a failure of BSS check 8.10.2 Are all appliance flues and exhausts complete and in good condition? This is an advisory check, so failure doesn't prevent a BSS certificate from being issued, but there may be issues with insurance cover (although obvious that depends a lot on the individual insurer).

 

Although in theory it might be possible to get a manufacturer to produce or endorse a dismountable flue for use on narrowboats, in practice I suspect most wouldn't in case somebody tried to use the appliance with the external flue dismounted.

Edited January 22, 2013 by Teadaemon