Jump to content

Back boiler Failure


DShK

Featured Posts

I once again come to seek the kindly wisdom of the people of this board.

 

Prerequisite info:

 

Morso Squirrel with backboiler

Gravity/thermosyphon system

Unpressured system with header tank

Stove front cabin, header tank mid cabin, above the calorifier

Heats calorifier first, then two radiators

 

Previously I posted about some advise about my stove. I threw in the question "I assume its normal for my backboiler to make some noise". It seemed not, and I had concluded I was overheating my stove. In hindsight, I was not. Since then I have tried long and hard to sort this out. I drained and run cleaner through the system. I have wondered if the boiler simply won't work without a full tank of water in the bow.

 

Sometimes I get nice circulation with hot water and radiators, sometimes the top pipe is very hot and the bottom pipe cold.

 

When I drained and added cleaner to the system, it seemed nice and quiet while I ran that through. I drained, flushed and refilled. Noises returned. These were "glug glug glugs", but now also included rapid ticking, and the pipes making rapid, intermittent knocks against the holes in the wood they passed through. Like they were expanding, but repeatedly. I also noticed the header tank needed a lot more topping up that it did before. I was having to top it up previously as air would escape the system with a lot of noise after I had initially filled it up. But now it was needing a decent amount without any noise. I knew something was wrong but there was not much I could do, considering it is -4C - I need the heating on.

 

Well last night I notice the backboiler leaking into the fire. I've drained the system and am currently without heat. 

 

I am at a loss as to how to proceed. I don't want to replace the rather expensive (and I gather hard to refit) boiler, if it's just going to fail again quickly. I assume that the boiler failed due to poor circulation, although part of me hopes that the boiler failed a while ago and that was causing the poor circulation. Otherwise, I can't tell if the poor circulation is the system being super sensitive to the amount of water ballasting my bow, or repeated airlocks, or some kind of blockage.

 

I assumed this system can work fine as the previous owner had the boat from new (his fit out) for 12 years. It could also be that this backboiler is 12 years old, I assume they have a limited lifespan?

 

I have considered that if I can conclude it is the trim issue, then I could fit a pump. Not ideal and not cheap, but it would solve the issue. If I were to go this route, how would I fit it? The pipe work is all copper. I assume I would need to cut this and fit some kind of flexible tubing?

 

 

Any advice for me here? I am a bit desperate as it's pretty damn cold. I am going to see if I can find an electric heater at least (going to be expensive to run!).

 

I can offer more info as needed, I can even make a quick 3d model of the pipework if it would help.

 

Thanks again.

Edited by DShK
Link to comment
Share on other sites

Can't help with the plumbing bit, but:

 

Our boiler leaked last year. It was only 4 years old. I put it down to corrosive fuel, and had a plate welded to the top of it. It is possible to remove it through the main door. I suppose it depends where yours is leaking from, but they are available to buy if you can't get it fixed.

 

ETA. Whilst our boiler was out for a few days, I covered over the boiler pipe holes with some sheet steel,by bolting through to another plate on the inside (with some high temp silicone) and ran it like that for a few days to keep warm. Not suggesting you do this.

Edited by rusty69
  • Greenie 1
Link to comment
Share on other sites

I think a leaking back boiler may well cause it to make noises and initially you may not notice the leak because it is evaporating away ro boiling off. What sized pipe work? With a boat trimmed down by the stern and the stove at the front it is not ideal in my view so if it is 22mm re-piping in 28 mm may help, but it is expansive with no guarantee success.

As calorifier coils are normally half way up then I suspect the up sweep  and the a down sweep for  one pipe and the opposite for the other may hinder gravity circulation. This assume the stove, calorifier and rads are in series, if the calorifie is T'd off the main pipe rns this will not apply.

  • Greenie 1
Link to comment
Share on other sites

19 minutes ago, DShK said:

I assumed this system can work fine as the previous owner had the boat from new (his fit out) for 12 years. It could also be that this backboiler is 12 years old, I assume they have a limited lifespan?

Was there corrosion inhibitor in the circulating fluid? Was it topped up, or changed regularly? Corrosion occurs on the inside and outside of the back boiler. At least with inhibitor, you know the inside should be OK.

 

  • Greenie 1
Link to comment
Share on other sites

5 minutes ago, Tony Brooks said:

I think a leaking back boiler may well cause it to make noises and initially you may not notice the leak because it is evaporating away ro boiling off. What sized pipe work? With a boat trimmed down by the stern and the stove at the front it is not ideal in my view so if it is 22mm re-piping in 28 mm may help, but it is expansive with no guarantee success.

As calorifier coils are normally half way up then I suspect the up sweep  and the a down sweep for  one pipe and the opposite for the other may hinder gravity circulation. This assume the stove, calorifier and rads are in series, if the calorifie is T'd off the main pipe rns this will not apply.

Okay, that sounds hopeful replacing the boiler might yield the solution as whole. 

The stove isn't fully at the front of the boat, about a couple of metres from the well deck. The top pipe seems to be 28mm with the bottom being 22mm. This is all one big loop, so in series, with a T junction for the header tank.

 

"calorifier coils are normally half way up then I suspect the up sweep  and the a down sweep for  one pipe and the opposite for the other may hinder gravity circulation"

 

Do you mean that the calorifier is perhaps causing the issue? Because I can get the water piping hot and the rads warm too, just not all the time (at least, anymore)

2 minutes ago, Jen-in-Wellies said:

Was there corrosion inhibitor in the circulating fluid? Was it topped up, or changed regularly? Corrosion occurs on the inside and outside of the back boiler. At least with inhibitor, you know the inside should be OK.

 

 

The previous owner just told me to top it up (with water). Never mentioned corrosion inhibitor. No idea if he used it, but when I've topped it up (and recently drained  and filled it) it's just been water. I topped it up regularly. Changed only recently but this is my first winter with it - can't speak for previous years. How often should I change it?

 

This is good to know, I will use corrosion inhibitor going forward, thanks.

Link to comment
Share on other sites

1 minute ago, DShK said:

Okay, that sounds hopeful replacing the boiler might yield the solution as whole. 

The stove isn't fully at the front of the boat, about a couple of metres from the well deck. The top pipe seems to be 28mm with the bottom being 22mm. This is all one big loop, so in series, with a T junction for the header tank.

 

"calorifier coils are normally half way up then I suspect the up sweep  and the a down sweep for  one pipe and the opposite for the other may hinder gravity circulation"

 

Do you mean that the calorifier is perhaps causing the issue? Because I can get the water piping hot and the rads warm too, just not all the time (at least, anymore)

 

I mean that with the calorifier between the stove and rads there is an upward or downward bow is which ever pipe feeds the calorifier coil. An upward bow in the return would tend to trap air in the coil, a downward bow in the feed would make the stove have to try to push cooled water in the coil up hill. I don't think either will help circulation. I think fitting Ts into the feed and return pipes  and linking the branch of the Ts to the calorfier will allow you to  keep the main feed and supply pipes at one level with no bows.

Link to comment
Share on other sites

22 minutes ago, DShK said:

How often should I change it?

Dunno. A bottle of inhibitor will probably say. I use a combined propylene glycol antifreeze and inhibitor, the same stuff used in the solar thermal hot water system I have. Dilute it to the recommended concentration and top up the open vented header tank with that when it gets low.

Edited by Jen-in-Wellies
Link to comment
Share on other sites

The boiler will come out through the door.  It helps to be a Zen Origami master who can do the Rubik's cube in 1 minute.  DAMHIKT.  You do need to remove the door and all the 'works' from the stove bottom, to ferkle the boiler out.

 

I find it quicker to take the lid off. Undo the boiler nuts and wriggle it forward and down to get at the lid bolts.  Put a strap round the body of the stove to hold it in shape with the lid off. Held by 4 bolts, near the corners, but you will probably have to grind the heads off.  The heat generated usually frees up the remains which can them be unscrewed with mole grips, or if not freed, drill out and re-tap.  Replace them with A4 stainless hex socket cap screws and a good dollop of copper grease.  IIRC they are M5.  Do not overdo the tightening as the stove needs to be able to give a little as it warms up and the plates expand.  You will probably need some new 7mm stove rope and glue to stick the rope to the lid.

 

There are two sorts of boiler: the originals were glass-lined steel.  The newer ones are stainless.  Any damage to the glass lining causes rapid failure.  Corrosive fuel causes pitting of the fire side but the lining survives.  Harworth heating or Morso Direct can supply and have given me good service.

 

Fill the system with 50% car antifreeze,  suitable for old engines,  50% water,  mixed before it goes in.  I use Morris's.  Change it like car antifreeze 2 or 3 yearly, or just add 500 ml  inhibitor, (Screwfix) to the antifreeze every couple of years.

 

If you empty the system and run the fire fairly gently it will be OK till you get a new boiler, because the old one is knackered anyway.

N

  • Greenie 1
Link to comment
Share on other sites

My backboiler makes a bit of noise and has been doing so over the last 18 winters. Usually it's just a gentle thumping noise but occasionally there's a bigger thump out two. I've added noise reducer. 

 

I'm wondering if it would matter if you just kept using the stove with the empty boiler during this cold snap until it's warm enough outside to do something about it? As long as the header tank is open and the system isn't pressurised would it damage anything more than is already damaged?

Link to comment
Share on other sites

A boiler run dry in a stove will proabably warp beyond redemption.

 

FIll it with sand - especially if you have any intention of getting repaired (i.e. if is a stainless one)

 

FWIW my new boiler - stainless, fitted this summer - makes a near continuous ticking noise. The old glass lined which (had lasted 20 or so years and only came out as a precaution because the stove had reached an age where it needed a full strip down) never made a sound.

  • Greenie 1
Link to comment
Share on other sites

2 hours ago, Tony Brooks said:

 

I mean that with the calorifier between the stove and rads there is an upward or downward bow is which ever pipe feeds the calorifier coil. An upward bow in the return would tend to trap air in the coil, a downward bow in the feed would make the stove have to try to push cooled water in the coil up hill. I don't think either will help circulation. I think fitting Ts into the feed and return pipes  and linking the branch of the Ts to the calorfier will allow you to  keep the main feed and supply pipes at one level with no bows.

I will make a quick 3D model when I have a mo and see if I can demonstrate what I have and see if I understand you correctly. Thanks!

2 hours ago, Jen-in-Wellies said:

Dunno. A bottle of inhibitor will probably say. I use a combined propylene glycol antifreeze and inhibitor, the same stuff used in the solar thermal hot water system I have. Dilute it to the recommended concentration and top up the open vented header tank with that when it gets low.

Okay good to know, thank you

1 hour ago, BEngo said:

The boiler will come out through the door.  It helps to be a Zen Origami master who can do the Rubik's cube in 1 minute.  DAMHIKT.  You do need to remove the door and all the 'works' from the stove bottom, to ferkle the boiler out.

 

I find it quicker to take the lid off. Undo the boiler nuts and wriggle it forward and down to get at the lid bolts.  Put a strap round the body of the stove to hold it in shape with the lid off. Held by 4 bolts, near the corners, but you will probably have to grind the heads off.  The heat generated usually frees up the remains which can them be unscrewed with mole grips, or if not freed, drill out and re-tap.  Replace them with A4 stainless hex socket cap screws and a good dollop of copper grease.  IIRC they are M5.  Do not overdo the tightening as the stove needs to be able to give a little as it warms up and the plates expand.  You will probably need some new 7mm stove rope and glue to stick the rope to the lid.

 

There are two sorts of boiler: the originals were glass-lined steel.  The newer ones are stainless.  Any damage to the glass lining causes rapid failure.  Corrosive fuel causes pitting of the fire side but the lining survives.  Harworth heating or Morso Direct can supply and have given me good service.

 

Fill the system with 50% car antifreeze,  suitable for old engines,  50% water,  mixed before it goes in.  I use Morris's.  Change it like car antifreeze 2 or 3 yearly, or just add 500 ml  inhibitor, (Screwfix) to the antifreeze every couple of years.

 

If you empty the system and run the fire fairly gently it will be OK till you get a new boiler, because the old one is knackered anyway.

N

Taking the top off sounds very involved and intimidating. I will try and take it out the front as a preference. But thank you for the guidance if I do go that way. And the advice on antifreeze etc. Much appreciated.

 

Shame that I have already started disassembling it all! I am off work for 2 weeks in a few days, it could have waited!

 

50 minutes ago, rusty69 said:

To add to the last comment,and my previous one, it can be done. I took this pic at the time to assist getting my boiler back in after welding:

IMG_20210425_165346107.jpg

 

Thanks. Can I ask, do the firebricks need to be removed? I thought I removed (broke) them, but there is a secondary, taller but thinner, set behind them. I can't seem to remove them with the backboiler in place, but it seems impossible to remove the boiler with them there. It looks the entire section the fire rests on has been removed? not just the grate? I wasn't aware you could do that.

 

20 minutes ago, blackrose said:

My backboiler makes a bit of noise and has been doing so over the last 18 winters. Usually it's just a gentle thumping noise but occasionally there's a bigger thump out two. I've added noise reducer. 

 

I'm wondering if it would matter if you just kept using the stove with the empty boiler during this cold snap until it's warm enough outside to do something about it? As long as the header tank is open and the system isn't pressurised would it damage anything more than is already damaged?

It might be fine, I have always been a bit worried that if there was an airlock before the header tank, it could build pressure up in the pipes (I'm not sure this is actually possible).

 

My concern would be a more catastrophic failure of the backboiler, I've seen a photo of someone's where water is flooding out of the stove! As mentioned above, I guess I could have emptied the system and run it, but too late now! I have popped to the shop to get an electric heater (I'm on a shoreline at the moment). It'll be expensive to use but hopefully I can get this sorted quickly.

4 minutes ago, Rose Narrowboats said:

A boiler run dry in a stove will proabably warp beyond redemption.

 

FIll it with sand - especially if you have any intention of getting repaired (i.e. if is a stainless one)

 

FWIW my new boiler - stainless, fitted this summer - makes a near continuous ticking noise. The old glass lined which (had lasted 20 or so years and only came out as a precaution because the stove had reached an age where it needed a full strip down) never made a sound.

Roger, thanks for the advice. Interesting, the thing I found offputting was the CHANGE in sound from mine. It didn't really make much ticking, but did make a lot of wooshing and glugging. Then it started ticking a lot when it wasn't making these sounds. Good to know that ticking is normal.

Link to comment
Share on other sites

Ours rarely makes much noise either unless the bottom door is left open too long and boils the water, which can be heard in the header tank. If its low on water it is much noisier. These gravity systems are great if setup properly, but can be quite sensitive if smaller bore pipe is added to the equation.

 

If it worked previously for 12 years for the last owners, and you have changed nothing, it seems a bit odd.

Link to comment
Share on other sites

2 minutes ago, DShK said:

Thanks. Can I ask, do the firebricks need to be removed? I thought I removed (broke) them, but there is a secondary, taller but thinner, set behind them. I can't seem to remove them with the backboiler in place, but it seems impossible to remove the boiler with them there. It looks the entire section the fire rests on has been removed? not just the grate? I wasn't aware you could do that.

Yes, I think one or perhaps both need removing. One of mine came out really easily, but I think I broke the other one in half. It depends how well centralised the boiler was on installation. I think I just used high temp silicone to glue the two halves back together when I installed the boiler.

I don't recall a brick further back, though if no backboiler is installed, a baffle plate and extra brick is used. The whole bottom plate can be removed; that is the bit above the ashpan iirc.

Link to comment
Share on other sites

 

image.png.fdbb98d8eeb39f19bb995e752aadb4fb.png

 

Here is a photo of where I am at for reference. The backboiler can lean forward and hit the sides of the front. The red circled bits are the secondary fire bricks which seem removeable but I can't seem to wiggle them out with the boiler in place. The bit above the ash pan seems held in place by the boiler and the bricks.

6 minutes ago, rusty69 said:

Ours rarely makes much noise either unless the bottom door is left open too long and boils the water, which can be heard in the header tank. If its low on water it is much noisier. These gravity systems are great if setup properly, but can be quite sensitive if smaller bore pipe is added to the equation.

 

If it worked previously for 12 years for the last owners, and you have changed nothing, it seems a bit odd.

Well, I think they must have had a lot of heavy stuff on board because I think it now sits a bit higher in the water. Perhaps the trim changed. But I am thinking that the problem was a failing boiler. There is a lot of crud in here, I just found a huge chunk of rotted steel... not sure where it came from yet, hopefully not the stove!

Link to comment
Share on other sites

1 minute ago, DShK said:

 

image.png.fdbb98d8eeb39f19bb995e752aadb4fb.png

 

Here is a photo of where I am at for reference. The backboiler can lean forward and hit the sides of the front. The red circled bits are the secondary fire bricks which seem removeable but I can't seem to wiggle them out with the boiler in place. The bit above the ash pan seems held in place by the boiler and the bricks.

Yeah the gap on the RH looks less than the LH side. I suspect you wont get the RH one out without breaking it.

4 minutes ago, DShK said:

Here is a photo of where I am at for reference. The backboiler can lean forward and hit the sides of the front. The red circled bits are the secondary fire bricks which seem removeable but I can't seem to wiggle them out with the boiler in place. The bit above the ash pan seems held in place by the boiler and the bricks.

Not sure what you mean by secondary bricks? They should be the only firebricks.

  • Greenie 1
Link to comment
Share on other sites

4 minutes ago, DShK said:

image.png.794aef4f26b9e3665f38dfcdabf8b465.png

 

There was something akin to an actual brick either side too. Perhaps these are not standard? If so, I wonder why they were added?

 

Oh, right. That just looks like a house brick or engineering brick to reduce the fire box size. Possibly why you weren't getting as much heat as you expected out of it earlier in the year.

Edited by rusty69
  • Greenie 1
Link to comment
Share on other sites

4 hours ago, DShK said:

Do you mean that the calorifier is perhaps causing the issue? Because I can get the water piping hot and the rads warm too, just not all the time (at least, anymore)

 With the calorifier in series with the stove and rads and between the stove &  rads it will take longer to get hot water into the rads, at first the calorifier will tend to take all the heat.

 

1 hour ago, DShK said:

will make a quick 3D model when I have a mo and see if I can demonstrate what I have and see if I understand you correctly. Thanks!

 

No need for a 3D model, Just a side view line diagram showing pipe runs and levels.

 

FWIW I don't think the 22mm return pipe will be helping much

Link to comment
Share on other sites

There could be a clue in the bit where it doesn't work without a full tank of water in the bow and as I understand the fire and boiler is nearly right at the front. My guess is that the system only just works. Gravity systems on narrow boats can struggle to get sufficient uphill slope to work because the damned boat slopes unhelpfully downhill to the stern. If the water tank at the bow is empty that tips the balance from working to not working. If the stove was at the back it would work wonderfully. I suggest a couple of concrete kerbstones right at the front. If the  boiler is steel it can be welded, if its cast iron its harder. For now Ii would disconnect the pipes to the boiler and just use the fire, some may suggest a firebrick at the back of the fire or filling it with sand but an empty disconnected boiler should be safe if disconnected, others might disagree but its too cold to have no heat

Link to comment
Share on other sites

2 hours ago, rusty69 said:

Oh, right. That just looks like a house brick or engineering brick to reduce the fire box size. Possibly why you weren't getting as much heat as you expected out of it earlier in the year.

Doh! Weird

 

1 hour ago, Tony Brooks said:

 With the calorifier in series with the stove and rads and between the stove &  rads it will take longer to get hot water into the rads, at first the calorifier will tend to take all the heat.

 

 

No need for a 3D model, Just a side view line diagram showing pipe runs and levels.

 

FWIW I don't think the 22mm return pipe will be helping much

I only say 3d model because I can hardly draw a straight line, and I make 3D models as part of my job. It's a much easier form of expression for me.

Water heating up first is no problem, the copper pipes are pretty decent rads themselves.

 

1 hour ago, ditchcrawler said:

Agree. its a bit like using 25mm positive cable and a 10 mm negative 

True!

 

Everything out and cleaned up! Looks a bit rough, lots of crud/corroded metal came off. But I think it's still healthy. Tomorrow I will buy new bits... so far so good. The boiler itself had a lot of sludge in it, so that cannot have been helping things....

image.jpeg.232fd5b0388e53ee8e8f0da547a1b2f1.jpeg

 

I went to clean the flue while I was doing it, and it seems the water leaking last night has spewed crud everywhere. This is WAY more corroded than it was before. It looks a bit like the stains from when people burn wood (that presumably is still wet). But I only burn excel.

 

image.jpeg.e5aa09193ec63a1f83cbd57d0af46320.jpeg

 

Chimney is ruined. The interior skin has fallen apart and crumbles in the hand.... again this is new....

 

image.jpeg.bf34de10af271b88d7390a8fe7ab2782.jpeg

 

Not only has the cruded filled liquid stained all along the hand rails, it's stained my paint work 😢 Anyone have any suggestions how I might be able to remove it?

 

image.png.70f071589849d504c710cbde7bd1f81a.png

 

Link to comment
Share on other sites

1 minute ago, DShK said:

Doh! Weird

 

I only say 3d model because I can hardly draw a straight line, and I make 3D models as part of my job. It's a much easier form of expression for me.

Water heating up first is no problem, the copper pipes are pretty decent rads themselves.

 

True!

 

Everything out and cleaned up! Looks a bit rough, lots of crud/corroded metal came off. But I think it's still healthy. Tomorrow I will buy new bits... so far so good. The boiler itself had a lot of sludge in it, so that cannot have been helping things....

image.jpeg.232fd5b0388e53ee8e8f0da547a1b2f1.jpeg

 

I went to clean the flue while I was doing it, and it seems the water leaking last night has spewed crud everywhere. This is WAY more corroded than it was before. It looks a bit like the stains from when people burn wood (that presumably is still wet). But I only burn excel.

 

image.jpeg.e5aa09193ec63a1f83cbd57d0af46320.jpeg

 

Chimney is ruined. The interior skin has fallen apart and crumbles in the hand.... again this is new....

 

image.jpeg.bf34de10af271b88d7390a8fe7ab2782.jpeg

 

Not only has the cruded filled liquid stained all along the hand rails, it's stained my paint work 😢 Anyone have any suggestions how I might be able to remove it?

 

image.png.70f071589849d504c710cbde7bd1f81a.png

 

Smokeless fuel composition has changed recently. It is what I have assumed made my boiler fail prematurely,but I have no proof. 

  • Greenie 1
Link to comment
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
  • Recently Browsing   0 members

    • No registered users viewing this page.
×
×
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue.