Back boiler Failure

[MtB]

8 minutes ago, BEngo said:

I suspect that the washer in the drain plug has come off the piece that you turn and is stuck to the seat.

 

There is a name for the bit that carries the washer - its called the "jumper".

 

 

[BEngo]

Thank you for reminding me of the right terminology.  Old age creepeth upon me. 

 In this case I think the washer may be having some time out from jumping!

N

 

[MtB]

1 hour ago, BEngo said:

Thank you for reminding me of the right terminology.  Old age creepeth upon me. 

 In this case I think the washer may be having some time out from jumping!

N

 

 

Indeed. I have extensive experience of drain cock <snigger> washers stuck to their seats. 

 

I deal with them buy first putting the hose on the outlet nozzle anyway. Then find a large flat blade screwdriver and a cloth/rag. Take the threaded plug out and the jumper may or may not come out with it. If it stays in, pull it out with long-nose pliers. Water will be spraying out at this point so use the rag to (mostly) hold it back and most will then go down the hose pipe. 

 

Next, grab the screwdriver and wrap the cloth around the stem of it, then shove it hard into the drain cock <snigger> and push the cloth up to again seal off the water spilling. Now push and rotate the screwdriver to gouge out and destroy the rubber washer to achieve full flow from the drain cock <snigger>. 

 

Now find the threaded plug and quickly remove the screwdriver and rag and put the plug back. This is where you get a bit wet until practiced at it. Wait for the appliance to fully drain then fit a new washer to the jumper and reassemble, or just fit a whole new drain cock <snigger>.

 

 

P.S. don't try this with a hot appliance!

 

 

[David Mack]

13 hours ago, BEngo said:

The way ahead is to reconfigure the radiator feeds so that hot water enters at the top and cooler water leaves at the base of each radiator. 

...so that the hot water enters at the top of the radiator directly from the top pipe...

Edited December 22, 2022 by David Mack

[David Mack]

11 hours ago, DShK said:

Radiator valves seem to always be designed with the pipework coming from the bottom - I'm assuming I just want a straight pipe, so just flipping my valve upside down is the best way to go?

Of you look inside a radiator valve you will see that even when fully open the hole through the valve is much smaller than the pipe leading to it. Fine on a pumped system, but will seriously restrict the flow with gravity circulation. Better to have no valves at all on the radiators, or if you do need the ability to shut a radiator down, then fit a full flow ball or gate valve on the pipework adjacent to the radiator.

[ditchcrawler]

On 22/12/2022 at 10:18, MtB said:

 

Indeed. I have extensive experience of drain cock <snigger> washers stuck to their seats. 

 

I deal with them buy first putting the hose on the outlet nozzle anyway. Then find a large flat blade screwdriver and a cloth/rag. Take the threaded plug out and the jumper may or may not come out with it. If it stays in, pull it out with long-nose pliers. Water will be spraying out at this point so use the rag to (mostly) hold it back and most will then go down the hose pipe. 

 

Next, grab the screwdriver and wrap the cloth around the stem of it, then shove it hard into the drain cock <snigger> and push the cloth up to again seal off the water spilling. Now push and rotate the screwdriver to gouge out and destroy the rubber washer to achieve full flow from the drain cock <snigger>. 

 

Now find the threaded plug and quickly remove the screwdriver and rag and put the plug back. This is where you get a bit wet until practiced at it. Wait for the appliance to fully drain then fit a new washer to the jumper and reassemble, or just fit a whole new drain cock <snigger>.

 

 

P.S. don't try this with a hot appliance!

 

 

I dont think I have ever had one not stick

[DShK]

Sorry for the radio silence. Was away from the boat for a while then I had to send away for some parts (as well as buying the wrong bits, who decided the measured size of a BSP fitting is 1/4" bigger than the part size??). It's been a huge pain to install but I've replumbed my radiators. This was a rather stressful affair! But I've removed the radiator valves as they definitely really did constrict down even when fully open. Both radiators are plumbed as BEngo suggested. The stove has been on for 3-4 hours,  the radiators are hot. The hot water is yet to show any signs of getting hot. The top pipe is hot, including the portion up to the header tank. The bottom pipe is cold. The back boiler still boils, although I feel like it took longer to start doing that.

 

Edit: If the system cools down a bit, it takes a while for the boiling to start again. It's definitely reach saturation. If I can get water moving through the hot water tank maybe it'll stop entirely....

 

I do wonder if the suggestion that the coil has failed/blocked may be correct? Surely if the radiators are getting nice and hot the system IS working. The water has got plenty hot in the past and now isn't even getting lukewarm.

 

What are my options now? I feel like my only choice is to get an expensive (money and power) circulation pump...

 

The radiators were filled with sludge so I wonder if the coil is too. I wonder if it's worth trying to blast water through the coil somehow....

 

I saw on another thread that it's possible for there to be an air pocket in the calorifier itself - is it possible that perhaps the coil is not submerged in water?

 

Edited January 15, 2023 by DShK

[Higgs]

9 hours ago, DShK said:

The stove has been on for 3-4 hours,  the radiators are hot. The hot water is yet to show any signs of getting hot. The top pipe is hot, including the portion up to the header tank. The bottom pipe is cold. The back boiler still boils, although I feel like it took longer to start doing that.

 

If the water is circulating from the top of the back boiler to the bottom of the back boiler, as it should, your boiler shouldn't boil. The colder water returning should be entering the boiler at the bottom and stopping the back boiler water from boiling. It would suggest a blockage or an air lock. If your boiler is boiling, I could imagine that the lower boiler fitting is also unusually hot. Can you sense whether the boiler's lower pipe cold return is hot for a few inches going away from the back of the boiler, caused by the conduction of heat produced by the back boiler?

 

If you have a pressure cap on the expansion tank, I would open it, when the system is no hot, then try again and see if the system works. I'd expect the water to expand and possibly overflow the header, if the boiler is boiling. The heat, you say, is rising all the way to the header, but you have not mentioned if the header is overflowing with hot water. This led me to think you might have a pressure cap on the header. If the drawing are anything to go by, you do not have a pressure cap. I've just looked them over. Can't understand what the pipe hanging over the header tank does. Any expanding hot water will just rise in the header from a bottom pipe. Any over flow will not have any space in the header, if that's what the top overhanging feed pipe is for. 

 

Do you have a drawing of the current arrangement?

 

 

 

 

 

Edited January 16, 2023 by Higgs

[Tony Brooks]

3 hours ago, Higgs said:

Can't understand what the pipe hanging over the header tank does.

 

I think that it is the vent pipe, that should be connected to the highest point in the system, to allow any air to escape. It helps in the bleeding of the system.

[BEngo]

The radiators are hot, so the water is circulating through them.  If the fire output to the boiler is greater than the heat output from the rads then, even though the water is circulating it will eventually boil.  Try running a pretty small fire.  If it keeps everything warm and does not boil you have cracked part 1- warmth.  Adding a couple of bricks to the sides of the fire so as to make a smaller firebox is a popular way to reduce the fire output.

 If the hot water is not delivering yet then the boiler water is not going through the calorifier, either because there is a sludge blockage as suggested above, or  because the route through the rads is easier than the route through the calorifier, or possibly because a valve near the calorifier is causing a resistance.

Acsludge blockagecsounds possible, given your experience with the rads.  To sort a sludge blockage put a hose from a tap on the calorifier outlet, another hose on the inlet and flush it through. Or take the calorifier out and hose it out on the bank.  You only need do the heating coil.

Then check any valves are not a problem. Replace any restrictive ones with full flow ball or lever valves.

If that gdoes not cure it you  can do one of two things- fit a full flow ball valve in each  radiator top pipe, and use these to balance the system so that flow through the calorifier is as easy as flow through the rads,  or try a circulation pump in the calorifier inlet and a cylinder thermostat to the calorifier to control the pump. When the pump is running you may not get much warmth out of the radiators as the pump is likely to push all the water through the calorifier.

 

Balancing the system is a matter of closing the ball valves a little bit at a time, waiting 15 minutes after each tweak,   until the hot water decides to go through the cal as well as the rads.

 

N

  

[Higgs]

1 hour ago, Tony Brooks said:

 

I think that it is the vent pipe, that should be connected to the highest point in the system, to allow any air to escape. It helps in the bleeding of the system.

 

Ah, ok. It still seems superfluous, as the air at that point would find its way up into the header from the lower header pipe. 

 

 

Edited January 16, 2023 by Higgs

[Higgs]

54 minutes ago, BEngo said:

The radiators are hot, so the water is circulating through them.  If the fire output to the boiler is greater than the heat output from the rads then, even though the water is circulating it will eventually boil. 

 

The bottom pipework is cold and should be feeding cold into the mix, at the bottom. If the bottom pipework is not even slightly warm, a rip-roaring fire should cause some heat to be noticeable at the bottom feed. I've had a Morso, with a back boiler, for 20 years. 

 

I used to have a pump on my system, it being slightly inefficient. The speed of the pump needed to be turned down, to allow for the water to pick up heat in the back boiler, which from a cold start takes time. Incoming water has been cooled along the way around the system, if a pump is pushing it around at speed, it has to remain in the boiler long enough to have heat transferred. The hotter the fire, the quicker the pump speed can be. 

 

If the radiators are completely warmed, the lower radiator outlets connected to the return pipe should be warm. If this is happening, you can probably rule out radiator problems. 

 

 

 

 

 

Edited January 16, 2023 by Higgs

[DShK]

No pressure cap on the header tank - it's open. The water level does expand and the water gets warm (it doesn't overflow as I don't overfill it!) Can't comment on the pipework around the header tank - BEngo suggested a better setup, which I will implement in the summer.

 

The bottom pipe is not warm at all, not even near the rads (I will double check this when the system is up to temp again this morning).

 

The stove does not boil until the rads are piping hot, so I think the system is being overwhelmed. I can run the stove at a higher temp before boiling than before. Although thinking about it, if the circulation was happening correctly, surely the bottom pipe would be hot too, before it got overwhelmed?

 

I think the hot water coil must be blocked because I have had plenty of hot water from it before, and I got none before this change and none after. The pipe entering the calofier is hot, so I would expect some heat from it - but none. I think I will make a fitting that I can connect that is just a stop-end and a drain cock so I can add a hose and blast water through a hose.

 

One thing of note is I don't think there is a consistent fall on the bottom pipe. It's mostly flat and but with some minor rises and falls. I'm not sure if this could make or break the system.

 

The setup is the same as before but the radiators are connected like this now (with no valves too).

Edited January 16, 2023 by DShK

[Higgs]

12 minutes ago, DShK said:

The stove does not boil until the rads are piping hot, so I think the system is being overwhelmed. I can run the stove at a higher temp before boiling than before. Although thinking about it, if the circulation was happening correctly, surely the bottom pipe would be hot too, before it got overwhelmed?

 

Yes. If the system was working that well, you would have the return pipe warming all the way to the back boiler. What you have sounds very similar to a thermostat not opening to allow water to circulate through a car's radiator. 

 

 

 

 

Edited January 16, 2023 by Higgs

[ditchcrawler]

24 minutes ago, DShK said:

 

 

One thing of note is I don't think there is a consistent fall on the bottom pipe. It's mostly flat and but with some minor rises and falls. I'm not sure if this could make or break the system.

If there is too much rise and fall you could have air in the high section.

[magnetman]

Air in the calorifier coil?

[DShK]

55 minutes ago, Higgs said:

 

Yes. If the system was working that well, you would have the return pipe warming all the way to the back boiler. What you have sounds very similar to a thermostat not opening to allow water to circulate through a car's radiator. 

 

 

 

 

There's definitely not a thermostat, at the very least between the radiators and the boiler.

 

34 minutes ago, ditchcrawler said:

If there is too much rise and fall you could have air in the high section.

Could be, it's fairly subtle. The worst section is a rise up to the boiler itself, so I would hope air would exit through the boiler. I also fill the system with a hose pipe on the bottom pipe now, with the vague hope the flow will stop air being trapped.

 

29 minutes ago, magnetman said:

Air in the calorifier coil?

 

Could be, I am thinking it's blocked somehow.

 

I don't know if sorting the hot water coil will solve the underlying issue or not, it might just increase the time/temp until the boiler boils. I think my next stop is see if I can unblock it and go from there...

 

If I have to fit a pump, this looks like my best option? All the others I've found look like they are for specific systems and won't fit inline nicely. It's so expensive though, does anyone know of one a bit more palatable on the wallet? https://www.jabscoshop.com/marine/pumps/circulation-pumps/59520-0000-8-12-volt-dc-ecocirc-pump-non-self-priming-for-hot-water-circulation.htm

Edited January 16, 2023 by DShK

[Higgs]

1 minute ago, DShK said:

There's definitely not a thermostat, at the very least between the radiators and the boiler.

 

No, just an analogy. 

 

 

[magnetman]

6 minutes ago, DShK said:

There's definitely not a thermostat, at the very least between the radiators and the boiler.

 

Could be, it's fairly subtle. The worst section is a rise up to the boiler itself, so I would hope air would exit through the boiler. I also fill the system with a hose pipe on the bottom pipe now, with the vague hope the flow will stop air being trapped.

 

 

Could be, I am thinking it's blocked somehow.

 

I don't know if sorting the hot water coil will solve the underlying issue or not, it might just increase the time/temp until the boiler boils. I think my next stop is see if I can unblock it and go from there...

 

If I have to fit a pump, this looks like my best option? All the others I've found look like they are for specific systems and won't fit inline nicely. It's so expensive though, does anyone know of one a bit more palatable on the wallet? https://www.jabscoshop.com/marine/pumps/circulation-pumps/59520-0000-8-12-volt-dc-ecocirc-pump-non-self-priming-for-hot-water-circulation.htm

 

I think there are some Chinese equivalents of this or the Johnson pump as is used on Mikuni heaters. 

 

Having said that it is an item which wants to be good quality. 

 

Brushless circulation pump as a search term I think might find something.

 

[David Mack]

2 hours ago, Higgs said:

 

Ah, ok. It still seems superfluous, as the air at that point would find its way up into the header from the lower header pipe. 

 

 

A single pipe from the highest point of the boiler/radiator circuit to the bottom of the header tank will work to allow air to escape. But a 2 pipe system, with a feed pipe from the header tank connecting to the bottom pipe of the boiler/radiator circulation, and an expansion pipe from the highest point to an inverted U above the header tank is a better solution. With this layout, if the boiler boils, steam and boiling water can escape via the vent pipe while cold water to replace it enters the system at the bottom. With a single pipe the two flows are in opposition.

In either case, if the boiler is boiling the fire needs to be damped down rapidly before any damage is done (or anyone is hurt by escaping steam or boiling water).

[DShK]

I just noticed that it's only the top of both radiators that's hot - not the bottom. This would explain why the bottom pipe isn't warm, the warm water isn't making it to the bottom pipe. Not sure what this is indictative of though. Obviously hot water rises, perhaps in this is because the radiators haven't been saturated yet and the heat is all released at the top. But I would expect the bottom to be at least a little warm?

[Jon57]

18 minutes ago, DShK said:

There's definitely not a thermostat, at the very least between the radiators and the boiler.

 

Could be, it's fairly subtle. The worst section is a rise up to the boiler itself, so I would hope air would exit through the boiler. I also fill the system with a hose pipe on the bottom pipe now, with the vague hope the flow will stop air being trapped.

 

 

Could be, I am thinking it's blocked somehow.

 

I don't know if sorting the hot water coil will solve the underlying issue or not, it might just increase the time/temp until the boiler boils. I think my next stop is see if I can unblock it and go from there...

 

If I have to fit a pump, this looks like my best option? All the others I've found look like they are for specific systems and won't fit inline nicely. It's so expensive though, does anyone know of one a bit more palatable on the wallet? https://www.jabscoshop.com/marine/pumps/circulation-pumps/59520-0000-8-12-volt-dc-ecocirc-pump-non-self-priming-for-hot-water-circulation.htm

There’s a Laing d5 12volt pump just the same as the pump above  half the price.

[Higgs]

 

13 minutes ago, DShK said:

I just noticed that it's only the top of both radiators that's hot - not the bottom. This would explain why the bottom pipe isn't warm, the warm water isn't making it to the bottom pipe. Not sure what this is indictative of though. Obviously hot water rises, perhaps in this is because the radiators haven't been saturated yet and the heat is all released at the top. But I would expect the bottom to be at least a little warm?

 

If both radiators are reacting the same, you could still rule out radiator problems. The flow on the return seems to be weak or non existent. 

 

 

Edited January 16, 2023 by Higgs

[magnetman]

41 minutes ago, David Mack said:

A single pipe from the highest point of the boiler/radiator circuit to the bottom of the header tank will work to allow air to escape. But a 2 pipe system, with a feed pipe from the header tank connecting to the bottom pipe of the boiler/radiator circulation, and an expansion pipe from the highest point to an inverted U above the header tank is a better solution. With this layout, if the boiler boils, steam and boiling water can escape via the vent pipe while cold water to replace it enters the system at the bottom. With a single pipe the two flows are in opposition.

In either case, if the boiler is boiling the fire needs to be damped down rapidly before any damage is done (or anyone is hurt by escaping steam or boiling water).

When I did a Rayburn in my narrow boat I led the flow pipe vertically straight out the top of the boat then ran it from a tee to the back of the boat along the deckhead lining. Header tank was plumbed to the return which was on the floor. Header tank recessed into the lining so that it was high enough and this was also vented to outside of boat. 

 

If the thing ever boiled over all of the steam and hot water was outside not inside. Seemed a better approach to me. 

 

Primary circuit was 28mm, no pump and I ran radiators and calorifier on 15mm pipes from flow and return pipes. Worked brilliantly. Best heating setup I've ever had but Jesus H Christ on a Jesus H bike did it go through the solid fuels ! You would need a small forest !

 

It was Alan at Uxbridge Boat Centre who told me to take the flow vertical to get the thermosyphon working as well as possible. Boat was slightly now up so the vent at the end of the flow pipe was the highest point and an open vent. 

Edited January 16, 2023 by magnetman

[Higgs]

48 minutes ago, David Mack said:

A single pipe from the highest point of the boiler/radiator circuit to the bottom of the header tank will work to allow air to escape. But a 2 pipe system, with a feed pipe from the header tank connecting to the bottom pipe of the boiler/radiator circulation, and an expansion pipe from the highest point to an inverted U above the header tank is a better solution. With this layout, if the boiler boils, steam and boiling water can escape via the vent pipe while cold water to replace it enters the system at the bottom. With a single pipe the two flows are in opposition.

In either case, if the boiler is boiling the fire needs to be damped down rapidly before any damage is done (or anyone is hurt by escaping steam or boiling water).

 

I can't see how you could expect water to flow back into the system from the header tank unless the system was cooling anyway and water from the header was being drawn back in as a consequence of cooling coolant fluid. Header tanks work that way, they are a reservoir for expanding liquid.

 

Edited January 16, 2023 by Higgs