Question: Narrowboat with back boiler feeding rads & calorifier

[Tasemu]

Hello again! I have a question I was hoping to get some advice on. I have used the search function to try and get as much info as possible but I am still unsure of the ramifications of this setup.

 

I'm going to try and keep this concise with a few points and questions about a boat and my girlfriend and I are seriously considering buying. We have been living on boats since march, but our water system has been a morco instant gas hot water so we have no experience with rads and/or calorifiers.

 

points:

• The boat is 52ft long
• There is a Morso Squirrel with a back boiler feeding 2 rads and a towel rail (i think)
• There is a calorifier fed by the engine and also the back boiler from the solid fuel stove

 

questions:

• Is a back boiler a reliable option for heating our hot water when moored for 14 days? (ccers for now)
• Would running the engine while the fire is lit cause a risk of the engine being damaged or overheated?
• In summer, if we wanted hot water without melting in the heat, are we out of luck or can we run the engine in idle to get hot water?
• Is this setup ok, or will it result in luke-warm radiators and luke warm water? (broad question i know sorry)
• If this setup is bad, is there a way to improve it? could a diesel water heater be installed into this setup, or would that conflict with the other heating supplies?

 

Sorry if this is a lot of questions. Thanks so much for any and all advice!

 

Edit: accidentally rated my own thread 5 stars

Edited January 30, 2020 by Tasemu

[Tony Brooks]

How hot the water from a back boiler gets is dependant upon the stoves size (rated output), how high you fire it and how hard you drive the fire.

 

As the boiler circuit in the calorifier is normally totally separate from the engine coil then there should be no danger of engine damage BUT if the skin tank is undersized a hot calorifier may allow overheating but that is the skin tank's fault.

 

Of course you can run the engine on idle but you would do far better to run it faster, especially if you are battery charging at the same time. (in neutral naturally).

 

You could install a diesel boiler as well but I don't see it will be worth it and you may have to complicate the system with valves so a runaway stove does not trip the boiler overheat system.

 

 

 

 

[Iain_S]

I'm assuming that the back boiler and engine feed separate calorifier coils.

 

 1 : I haven't used a similar set up, but we found that an Alde could heat either water or radiators effectively, but radiator output was much reduced initally, improving as the calorfier got up to temperature.

 

 2 : No

 

3: Yes. It will work better if the engine is dong some work, though, like charging batteries. Also works better if engine doing a bit more than idle, although this depends a bit on how good the cooling system is.

 

4 ; Quite possibly. Can you switch the radiators off, so that the back boiler is heating water only? Do you need radiators when the stove is on?

 

5: Nothing wrong on the face of it, but insufficient information. Is there a pump in the system, if so, how is it controlled? Must it be running if stove lit? etc, etc. Try "as is" , and if there are shortcomings, then think about fixing them! Adding a diesel water heater could pssibly be done, Would need careful design, though, and possibly an extra calorifier coil.

 

Edited January 30, 2020 by Iain_S
mising lettrs

[LadyG]

I have a stove with backboiler, it provides hot water and takes chill off bathroom [small radiator], the pipes also keep a small airing cupboard, and the bedhead dry and warm.

My stove [unbranded] would be running far too hot to heat two bigger rads imho.

I have a Webasto which I have just started up, the water is now piping hot and it looks after itself, pretty much kicking in when stove goes out.

I am no longer a slave to the stove, cabin temperature is controllable,  it should be more economical, and if we hit a cold spell, it will cope. I am on a shoreline, and run an old fashioned  built-in charger [no programming], about 18 hours per day [it makes an annoying noise]. If I am doing it wrong, please tell me about it ?

 

Edited January 31, 2020 by LadyG

[Tony Brooks]

30 minutes ago, LadyG said:

I have a stove with backboiler, it provides hot water and takes chill off bathroom [small radiator], the pipes also keep a small airing cupboard, and the bedhead dry and warm.

My stove [unbranded] would be running far too hot to heat two bigger rads imho.

I have a Webasto which I have just started up, the water is now piping hot and it looks after itself, pretty much kicking in when stove goes out.

I am no longer a slave to the stove, cabin temperature is controllable,  it should be more economical, and if we hit a cold spell, it will cope. I am on a shoreline, and run an old fashioned  built-in charger [no programming], about 18 hours per day [it makes an annoying noise]. If I am doing it wrong, please tell me about it ?

 

Depends on how old fashioned the charger is. If it is a two or more stage charger then fine but if its really old fashioned then the voltage will rise as the batteries charge and in 18 hours MIGHT (not will) rise enough to damage the batteries but more likely after  couple of days on charge. This also depends upon the charge output and bank size. Its a bit like your stove. You seem to have got the measure of it  but unless the OP tells us his stoves rated back boiler output we are only guessing.

 

[Alan de Enfield]

20 minutes ago, Tony Brooks said:

Depends on how old fashioned the charger is. If it is a two or more stage charger then fine but if its really old fashioned then the voltage will rise as the batteries charge and in 18 hours MIGHT (not will) rise enough to damage the batteries but more likely after  couple of days on charge.

I have an 'old' Halford's charger , it's only about 4 amp but the voltage just goes up, and up and up, I use it for equalisation occasionally but the most I've ever let it get to is 16v, I don't know how much higher it would go if left unattended.

[Tasemu]

13 hours ago, Iain_S said:

I'm assuming that the back boiler and engine feed separate calorifier coils.

 

 1 : I haven't used a similar set up, but we found that an Alde could heat either water or radiators effectively, but radiator output was much reduced initally, improving as the calorfier got up to temperature.

 

 2 : No

 

3: Yes. It will work better if the engine is dong some work, though, like charging batteries. Also works better if engine doing a bit more than idle, although this depends a bit on how good the cooling system is.

 

4 ; Quite possibly. Can you switch the radiators off, so that the back boiler is heating water only? Do you need radiators when the stove is on?

 

5: Nothing wrong on the face of it, but insufficient information. Is there a pump in the system, if so, how is it controlled? Must it be running if stove lit? etc, etc. Try "as is" , and if there are shortcomings, then think about fixing them! Adding a diesel water heater could pssibly be done, Would need careful design, though, and possibly an extra calorifier coil.

 

 

4: I'm not sure, i think you could turn them off by totally restricting the flow through them, or do you mean a valve to isolate them seperately?

 

5: There is a pump, it is 12v and controlled from the stern entrance. I believe it has to be running to circulate the water in the back boiler, is that bad?

 

Thanks for all the advice everyone.

[Tony Brooks]

4. For safety reasons (boiling) it is not wise to run a stove with back boiler designed to run a calorifier and rads with the rads turned off unless the stove is thermostatically controlled and has a boiler overheat shut down on it - none have as far as I know.

 

5. See 4 above for reason. Although thee are many pumped stove systems its safer and uses less electricity if a stove is connected to a gravity (thermo-siphon) heating circuit. At the very least you should have a pipe stat at the stove outlet so that it can overrode the pump switch in case you forgot to turn the pump on.

[Tasemu]

40 minutes ago, Tony Brooks said:

4. For safety reasons (boiling) it is not wise to run a stove with back boiler designed to run a calorifier and rads with the rads turned off unless the stove is thermostatically controlled and has a boiler overheat shut down on it - none have as far as I know.

 

5. See 4 above for reason. Although thee are many pumped stove systems its safer and uses less electricity if a stove is connected to a gravity (thermo-siphon) heating circuit. At the very least you should have a pipe stat at the stove outlet so that it can overrode the pump switch in case you forgot to turn the pump on.

4: So if I wanted to heat my water I should ensure the pump is on and the rads are not isolated to ensure that it wont boil? Just checking I have it right.

 

5: I'm not sure about this, according to the marina guy i should have the pump running for it to work. So i'm assuming there is no siphon ability in the sytem or an override pipe. Is this very bad or just important that I run the pump always?

 

Thanks for the help mate.

[Tony Brooks]

4. Yes, that is right but if you turned the rads off with a small dying fire and a cold calorifier it would probably not boil. Its all to do with heat into the water from the fire and heat out from the rads and calorifier coil.

 

5. Yes, you must have the pump running on your system to avoid boiling and the potential for an explosion or hot rusty antifreeze water spraying everywhere. It is not an ideal system but similar to many. There is no fail safe apart from an open header tank and/or safety valve for the occasion when the pump fails, it is not switched on, or the fire runs away - and they often can in high winds. The idea of a pipe mounted thermostat is to try to remove the danger of humans forgetting to turn the pump on when they light the fire or inadvertently turning it off. Iam not talking about any extra pipes, google "pipe thermostat" - https://www.screwfix.com/p/flomasta-cylinder-thermostat-230v/6803K?tc=QT6&ds_kid=92700020953274762&ds_rl=1241687&ds_rl=1245250&ds_rl=1249404&ds_rl=1249799&ds_rl=1245250&ds_rl=1249481&gclid=EAIaIQobChMI7bmA9eat5wIVhrTtCh2f7Q8bEAQYCiABEgJyXfD_BwE&gclsrc=aw.ds

 

However as that is probably an AC switch for longevity it might need pairing with a relay but that's complicating things. I suspect most people just hope they do not forget to turn the pump on.

[LadyG]

On 31/01/2020 at 08:14, Tony Brooks said:

Depends on how old fashioned the charger is. If it is a two or more stage charger then fine but if its really old fashioned then the voltage will rise as the batteries charge and in 18 hours MIGHT (not will) rise enough to damage the batteries but more likely after  couple of days on charge. This also depends upon the charge output and bank size. Its a bit like your stove. You seem to have got the measure of it  but unless the OP tells us his stoves rated back boiler output we are only guessing.

 

That rings bells, day 3/4 of charging and the peak voltage is steadily creeping up to alarming levels, I'll go back charging when the Webasto kicks in ....... now a slave to a machine, is this wot Orwell was thinking would happen as we humans race to the precipice?

There are five lights, red/amber/amber/green/another. The first one and the fourth are on, will have another look in 30 mins.

I will make a note of today's 16v as "equalisation"

I do have a 5 amp CTEK which I would happily leave on if I am not aboard.

Edited February 1, 2020 by LadyG

[Tony Brooks]

32 minutes ago, LadyG said:

That rings bells, day 3/4 of charging and the peak voltage is steadily creeping up to alarming levels, I'll go back charging when the Webasto kicks in ....... now a slave to a machine, is this wot Orwell was thinking would happen as we humans race to the precipice?

There are five lights, red/amber/amber/green/another. The first one and the fourth are on, will have another look in 30 mins.

I will make a note of today's 16v as "equalisation"

I do have a 5 amp CTEK which I would happily leave on if I am not aboard.

If it has five lights it probably is a multi-stage charger but that does not mean its not faulty. The top light probably means it turned one and each of the others shows the type of charge its doing - bulk, acceptance, float, or equalise but I doubt it should equalise every day. I would expect the voltage to normally peak at no more than 14.6 ish