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Which type of antifreeze do people use in their back boilers?


Piran

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We have an open (not sealed) system with pressure release valves and pump that heats three radiators, fuelled by Morso Squirrel stove with back boiler. It is used to heat the radiators but isn't not used to heat our water.
We hadn't worked all of this out last night when first lighting the stove, so stupidly, we didn't turn on the pump or top up the empty header tank. The pressure relief valve nearest the stove started spewing steam, and radiators didn't heat up. So we killed the fire.
We want to try again tonight having realised these mistakes but we are concerned about which type anti freeze to use. Is it a bad idea to use standard (toxic) anti freeze in a system with pressure release valves? Just thinking about whether something else might cause steam to escape again on the second attempt. I know you can get a propylene glycol based anti freeze typically used in water heater systems but seems harder to get hold of quickly.
 
Any thoughts welcome, cheers!
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8 minutes ago, Piran said:
We have an open (not sealed) system with pressure release valves and pump that heats three radiators, fuelled by Morso Squirrel stove with back boiler. It is used to heat the radiators but isn't not used to heat our water.
We hadn't worked all of this out last night when first lighting the stove, so stupidly, we didn't turn on the pump or top up the empty header tank. The pressure relief valve nearest the stove started spewing steam, and radiators didn't heat up. So we killed the fire.
We want to try again tonight having realised these mistakes but we are concerned about which type anti freeze to use. Is it a bad idea to use standard (toxic) anti freeze in a system with pressure release valves? Just thinking about whether something else might cause steam to escape again on the second attempt. I know you can get a propylene glycol based anti freeze typically used in water heater systems but seems harder to get hold of quickly.
 
Any thoughts welcome, cheers!

Your on the wrong forum to use a font that size!! Most of us on here cant even read that even with our glasses on!!

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Avoid mixing blue with red but different makes should be fine, garages never bother when they top up. The red is now standard auto stuff, should be easy to get.

 

I hate solid fuel systems that rely on a pump for circulation, you have found out why.

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33 minutes ago, Piran said:

Thanks Tonka, would it be advisable to drain the system prior to adding the new solution or is this not necessary? not sure what was used in there before 

I would drain it first so as to be sure that when you fill it will be mixed properly. Unmixed antifreeze can jam the system. Alphi 2 is clear by the way.

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14 minutes ago, Piran said:

Great, thanks will do. Just trying to locate the drain, any clues on where they are usually situated? 

 

Cheers again

Hopefully at the lowest point in the circuit. The fun will start trying to collect the water without it draining into the bilges.

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In my open vented back boiler central heating I use this stuff.

https://www.screwfix.com/p/flomasta-0623-concentrated-central-heating-inhibited-antifreeze-5ltr/4409r

Propylene Glycol is used for the antifreeze component, so is non toxic. I'd drain it down and fill from empty, so you know you've got the concentration right. You may find air locks afterwards that need bleeding out. The anti corrosion components are as important as the antifreeze one, if not more so and this has them too. Screwfix have branches in cities and towns of any appreciable size.

Jen

Edited by Jen-in-Wellies
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56 minutes ago, Jen-in-Wellies said:

In my open vented back boiler central heating I use this stuff.

https://www.screwfix.com/p/flomasta-0623-concentrated-central-heating-inhibited-antifreeze-5ltr/4409r

Propylene Glycol is used for the antifreeze component, so is non toxic. I'd drain it down and fill from empty, so you know you've got the concentration right. You may find air locks afterwards that need bleeding out. The anti corrosion components are as important as the antifreeze one, if not more so and this has them too. Screwfix have branches in cities and towns of any appreciable size.

Jen

I used the same in my solid fuel gravity system. I mixed it beforehand to 25% mix. Poured it into header tank with a jug. So far 7 years later all ok.  Your drain off could be on the radiator valve itself or in the pipework. I bleed my rads again a few weeks after refilling.

 

James.

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10 hours ago, canals are us? said:

I used the same in my solid fuel gravity system. I mixed it beforehand to 25% mix. Poured it into header tank with a jug. So far 7 years later all ok.  Your drain off could be on the radiator valve itself or in the pipework. I bleed my rads again a few weeks after refilling.

 

James.

Good points. I too premixed a few litres at a time to 25%, 1 part antifreeze to 3 parts water, in a jug and poured it in. Premixing is important as otherwise they tend to stratify in the system and not mix properly. If the OP is in a hard water area then it could make sense to use deionised water. On mine, the drain point is by the stove, under the bottom back boiler connection as this is the lowest point. Radiators will need bleeding to remove air when the pump is started and also when the fire is first lit. Have more mixed antifreeze to add to the header tank to keep the level up.

Jen

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4 hours ago, Jen-in-Wellies said:

Good points. I too premixed a few litres at a time to 25%, 1 part antifreeze to 3 parts water, in a jug and poured it in. Premixing is important as otherwise they tend to stratify in the system and not mix properly. If the OP is in a hard water area then it could make sense to use deionised water. On mine, the drain point is by the stove, under the bottom back boiler connection as this is the lowest point. Radiators will need bleeding to remove air when the pump is started and also when the fire is first lit. Have more mixed antifreeze to add to the header tank to keep the level up.

Jen

 

Its important not to go higher than a 25% concentration of antifreeze, or the radiators won't get hot.

 

I initially made up a 50% solution to do the engine and the central heating.

 

Filled both systems and switched the Webasto boiler on but the radiators didn't  get warm.

 

Heated each radiator in turn with a hot air gun and the system worked fine, until I turned it off. Needed the hot air gun to get the circulation going every time. 

 

Drained the system, reduced the concentration to 25%, refilled and tried again and everything worked as intended.

 

 

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24 minutes ago, cuthound said:

 

Its important not to go higher than a 25% concentration of antifreeze, or the radiators won't get hot.

 

I initially made up a 50% solution to do the engine and the central heating.

 

Filled both systems and switched the Webasto boiler on but the radiators didn't  get warm.

 

Heated each radiator in turn with a hot air gun and the system worked fine, until I turned it off. Needed the hot air gun to get the circulation going every time. 

 

Drained the system, reduced the concentration to 25%, refilled and tried again and everything worked as intended.

 

 

 

That sounds far more although you left some unmixed water in the system. It won't matter what density the liquid is in a gravity system as long as it is all the same.  When you heat it it becomes less dense so rises to the top of the system and will then fall as it cools and becomes more dense. Its when you have liquids of different densities in a system that circulation will not take place because the denser liquid (antifreeze) when hot is still not less dense than the cold less dense liquid (water) so can't rise in the system. Its trapped below the cold less dense liquid. I have had no problem getting circulation in a gas fired gravity system with 50% antifreeze.

 

Where you may have problems with high concentrations of antifreeze is that antifreeze has a lower specific heat than water so the more you add the less heat it can carry around the system this is why in engines it is not a good idea to go above 50%.

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1 minute ago, Tony Brooks said:

 

That sounds far more although you left some unmixed water in the system. It won't matter what density the liquid is in a gravity system as long as it is all the same.  When you heat it it becomes less dense so rises to the top of the system and will then fall as it cools and becomes more dense. Its when you have liquids of different densities in a system that circulation will not take place because the denser liquid (antifreeze) when hot is still not less dense than the cold less dense liquid (water) so can't rise in the system. Its trapped below the cold less dense liquid. I have had no problem getting circulation in a gas fired gravity system with 50% antifreeze.

 

Where you may have problems with high concentrations of antifreeze is that antifreeze has a lower specific heat than water so the more you add the less heat it can carry around the system this is why in engines it is not a good idea to go above 50%.

 

Definately not. I mixed up enough antifreeze and water (in two 25 litre containers) by adding a litre of antifreeze, then a litre of deionised water to fill both systems.

 

When the central heating didn't work, I used a hot air gun to heat up each radiator, and the system warmed. I left it running for several hours, which would have thoroughly mixed it.

 

I repeated the exercise the next day, before biting the bullet to drain and refill the system with a weaker concentration.

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3 minutes ago, peterboat said:

I use pink antifreeze in my system which seems to have worked ok over the last ten years, it has been changed once as the anti corrosion part doesnt last forever.

 

Yes I used the Ford Super Plus Premium 10 year life antifreeze.

 

I check it annually by putting some extracted from the engine into an old plastic bottle along with a snip of copper, aluminium and a rusty nail. If the nail doesnt go rusty I pop it in the freezer to see if it freezes. If not I leave it in for another year. 6 years since I changed it so far.

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3 hours ago, cuthound said:

 

Definately not. I mixed up enough antifreeze and water (in two 25 litre containers) by adding a litre of antifreeze, then a litre of deionised water to fill both systems.

 

When the central heating didn't work, I used a hot air gun to heat up each radiator, and the system warmed. I left it running for several hours, which would have thoroughly mixed it.

 

I repeated the exercise the next day, before biting the bullet to drain and refill the system with a weaker concentration.

All I can say is that it makes no sense physics wise but you found what you found.

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I have been really struggling to find the drainage point in my system. I have traced the pipe work around the boat and under most of the floor boards I can get up without breaking them. Would anyone be able to send a picture of their drainage points so I might get a slightly better idea of I do find it?

 

 

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6 hours ago, Piran said:

I have been really struggling to find the drainage point in my system. I have traced the pipe work around the boat and under most of the floor boards I can get up without breaking them. Would anyone be able to send a picture of their drainage points so I might get a slightly better idea of I do find it?

 

 

Something like this:

15-mm-spigot-drain-cock-brass-6_min_2130

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right so after a lot of searching and a call with the previous owner I have realised that I actually have a closed, pump system. After experiencing an (electrical) pump failure yesterday we are quite keen to just disconnect the back boiler and use the stove on its own. Would rather just have the stove without the stress of the back boiler at this point. Any tips for disconnection? Wondering if we can just unscrew the back boiler entry and exit pipes and let the liquid in the back of the stove burn off or if we need to drain the entire system and remove all the pipe work? 

 

Getting pretty chilly so keen to get the fire on !

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3 hours ago, Piran said:

right so after a lot of searching and a call with the previous owner I have realised that I actually have a closed, pump system. After experiencing an (electrical) pump failure yesterday we are quite keen to just disconnect the back boiler and use the stove on its own. Would rather just have the stove without the stress of the back boiler at this point. Any tips for disconnection? Wondering if we can just unscrew the back boiler entry and exit pipes and let the liquid in the back of the stove burn off or if we need to drain the entire system and remove all the pipe work? 

 

Getting pretty chilly so keen to get the fire on !

I find it all but unbelievable that an idiot would fit a closed (sealed) system with a  solid fuel stove. It not far short of a bomb so are you sure its a sealed system, if not what do you mean by a closed system.

 

Some/may back boilers are said to be glass lined and if yours is doing what you suggest is likely to shatter the glass. If the boiler s thin mental it may melt or distort. Neither are a problem if you never want to use the boiler again. If you take a pipe off and let all the liquid out then as long  as you leave it disconnected so any steam can escape it shoudl be OK but until you boil off  the residual liquid in the boiler you will make a lot of steam and condensation.

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