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Calorifier plumbing - what is the 1/2" female tapping for?


jetzi

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What are the 1/2" female tappings for on my calorifier?

 

I've tried to find diagrams of calorifier plumbing online (including at Tony Brooks' site here: http://www.tb-training.co.uk/17Bdomwat.html ) but I can't see anywhere shows this fitting.

 

I think the top one is for fitting the pressure relief valve (so you don't have to fit it on the hot water outlet?), and my guess is that the bottom one to allow a point to drain the tank for winterisation etc.

 

Can I blank them off with with a 1/2" BSP stopper? And could I fit the PRV on the 22mm outlet to a T on the top of the tank? The way my boat is laid out makes it awkward to fit the PRV on that fitting, if that is what it's for.

 

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Typically the PRV would have been fitted into a T in the top 22mm fitting. A 1/2" female fitting would create a restriction to the hot water outflow so I would not use it as the hot water outlet but you could fit the PRV into it. I can think of things you could use either 1/2" fitting for bu can't see why you would. I think you need to ask the suppliers if no one here knows.

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For what it's worth my boat appears to have a calorifier of exactly the same arrangement.  The very top fitting is used exclusively for the hot water outlet the half inch fitting on the bottom is utilised for the PRV.  My boat is a 2004 Measham, I very recently changed my PRV as it was passing causing the water pump to start up twice in the middle of the night.  The PRV was (is) rated at 2 bar about £18.00 from memory from Midland chandlers.

The system was and now is working perfectly.

Hope this helps.

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Bottom 1/2" can be the drain, I would use the top one for the hot to the shower, avoids the very hot water at the top.    PRV in the hot take off the crown.

!5mm pipe is fine, you only have 15mm cold feed in so no point in going larger on the hot out.

Incidentally I would reverse your coils flow and return, it will be 6% more efficient and easier to get the air out if the top is the return.

Are you fitting a thermostatic blending valve in whilst you are at it?

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Thanks, it does help. So your calorifier doesn't use the hot water outlet on the very very top of the tank - you rather take the hot water from the top female fitting on the side?

 

I think there can be no harm in putting stoppers on them then and using a "normal" calorifier arrangement, with a T on the top for water and PRV.


Tony, since you've been kind enough to answer perhaps I could ask you to clarify something from your website:
 

Quote

When the engine-cooling thermostat opens it is possible for water flow through the calorifier to stop because heat exchanger/skin tank/keel cooler provides an easier path. To minimise this risk connect the HOT (away from the engine) pipe to the higher calorifier "coil" connection and the return to the lower one. Try to ensure both connections run horizontally at the calorifier end to prevent thermo-siphoning of water from the coil, backwards through the engine once the engine has been turned off.
 

If you find that the engine room calorifier pipes/hoses are still hot some time after turning the engine off and only cool water in the morning it will be because of thermo-siphoning. The best thing to try is swapping the upper and lower connections over. This usually cures it, but you might lose calorifier operation when the engine thermostat is open – only experimentation will tell.

I assume that the cooling pipes leading out of the top of the engine are the outlets (since heat rises). I have two outlets on the top of my Beta 38 engine, located on opposite sides. There's a small 15mm one which leads to the bottom fitting of my old calorifier coil on one side. On the other side is a very large one which leads to the top of one skin tank, then out the bottom of that skin tank to the top of the other skin tank, then out of the bottom of that skin tank to the bottom of my engine. Where the large skin tank pipes rejoin the engine, there is also a smaller inlet to receive the return (I assume) feed from the top of the calorifier coil. Since the pipes meet here, I presume this must be where the thermostat is. I find that a bit confusing because I would have thought that it would be located on the outlet of the engine.

 

The new calorifier is located in the engine bay on top of the swim. This means the pipe run is much shorter than previously and I was thinking of using flexible hoses (50cm from the top of the engine to the bottom of one coil, and about 1.5m from the top of the coil back to the engine. Since the engine is lower than the calorifier, both pipes will be sloped. I think a bleed valve on the top outlet of the calorifier coil will be necessary to get any air out (where the arrow is in the diagram).

 

I'm not sure exactly what it means for the pipes to run horizontally or if that's possible in my case. Thisis how the old calorifier is arranged and it's working well. Considering that now the calorifier is going to be higher than the engine coolant tank on top of the engine, is this still going to work? Will it be prone to thermosiphoning back into the engine when the engine is off?


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6 minutes ago, Tracy D'arth said:

Incidentally I would reverse your coils flow and return, it will be 6% more efficient and easier to get the air out if the top is the return.

Interesting that it's more efficient! Yeah that's the diagram from the manufacturer of the calorifier, but my existing calorifier (I think) has the return at the top. No bleed valves on my current system but so far so good.

 

7 minutes ago, Tracy D'arth said:

Are you fitting a thermostatic blending valve in whilst you are at it?

To reduce the temperature of the hot water out of the tank? All my taps are blenders actually and I have a thermostatic blender which I plan to use for the washing machine inlet. So I don't think it's necessary to "globally" reduce the temperature. So far at least the water from my taps has never been too hot.

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Your calorifier take off is on the  engine side of the thermostat so as long as the stats is closed water will be pumped to to the calorifier. As soon as the stat is open far enough the resistance in the calorifier  circuit may cause the flow through the calorifier the reduce or stop. This is more likely if the calorifier is half way up the boat. In your case it is unlikely but if it did happen using thermo-syphoning to assist the water flow through the coil can often help. That is allowing the cooling water in the coil to sink and draw hot water out of the engine.The other problem is that with a cooling engine the water in the coil can thermo-syphon through the engine or skin tank. If this happens piping as Tracy says may stop it and it may if the pipe from the coil to the top of the engine runs horizontally for a short distnace rather than upwards. If not a flap valve in the supply pipe (get it the correct way round) will usually stop it. It is important not to pipe the coil circuit in a way that allows air to be trapped in loops or high points. If the installation can not avoid this fit a bleed valve (not automatic) at the highest point so you can vent the air.  I don't understand why you intend to use 50mm hose for one of the coil circuit legs. 50mm is typically main cooling circuit skin tank pipes. Calorifier coil pipes are more usually !/2" or 5/8", often car heater hose.  I very much doubt you will notice an theoretical improvement in efficiency because when the engine is heating the calorifier it is usually doing other things like charging the batteries or moving the boat.  In my view its more important to get reliable circulation and no thermo-syphoning when the engien is off.

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1 hour ago, Tony Brooks said:

Your calorifier take off is on the  engine side of the thermostat so as long as the stats is closed water will be pumped to to the calorifier.

I think I get it! The thermostat is used to close the skin tanks when the temperature of the engine is less than X.  Excess heat from the engine goes into the calorifier, until the engine is too hot to be cooled by the calorifier circuit alone, at which point the thermostat opens the skin tanks.

 

1 hour ago, Tony Brooks said:

In your case it is unlikely but if it did happen using thermo-syphoning to assist the water flow through the coil can often help.

...

piping may stop it and if the pipe from the coil to the top of the engine runs horizontally for a short distnace rather than upwards.

...

its more important to get reliable circulation and no thermo-syphoning when the engien is off.

Alright, so since my calorifier is very close to the engine, I probably won't have a problem with flow. Pro of mounting the cali in the engine bay.

 

Taking all this into account, I'll have the flow from the top of the engine enter the top of the coil (how my old calorifier is currently configured). This should assist the water to flow via thermosiphon and discourage water that is heated in the calorifier from flowing back to the engine. If that doesn't work, then I'll have to add a flap valve (How will I know that it's not working? Hot water cools quickly?)
 

1 hour ago, Tony Brooks said:

I don't understand why you intend to use 50mm hose for one of the coil circuit legs. 50mm is typically main cooling circuit skin tank pipes. Calorifier coil pipes are more usually !/2" or 5/8", often car heater hose. 

I'm not. Currently the engine is connected by hoses (15mm inside diameter ID, 20mm outside diameter OD) to 15mm pvc pipes, then a push-fit reducer to take the pipes to 22mm pipework to the calorifier where they go through another reducer to fit the old cali's 15mm coils. I don't really have space for horizontal pipes from the cali's coils so hopefully these aren't needed.


For the new calorifier I'm going to try the following:

 

* 15mm OD engine pipe outlets go to:
* short piece of 15mm hose with a jubilee clip. (I'll reuse some of my existing 15mm ID hose).

* 15mm/22mm brass hose reducer with jubilee clips.

* 22mm ID car radiator hose (this one is silicone. I can cut a 1m and 2m length for the flow and return, respectively). I figure it's best to have the same bore as the calorifier coil, even if the outlet of the engine is smaller.

* Connect via jubilee clip to a short bit of 22mm OD PVC pipe on the end to make the connection with the compression fittings on the calorifier (using inserts of course).

 

I'll make sure the hoses are always rising from the engine to the calorifier. I'll attempt to bleed by slacking off the jubilee clip on the top pipe calorifier coil (the flow side). If that doesn't work then I might need to look at including a dedicated bleed valve. I'll have a mixture of coolant ready which I'll pour into the top of the engine while I do this.

 

Can you see any reason this plan might not work?

Edited by ivan&alice
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Answers in order above:

 

1. Yes, that's it

 

2. Hot water into the TOP of the  coil will encourage thermo-syphoning when cold. One cure worth a try is to reverse the flow through the coil as Tracy said - hot into the bottom of the coil and cold out the top.

 

3 If the water in the calorifier cools faster than expected or if  an hour or so after stopping the calorifier pipe are warm its thermo-syphoning.

 

4. It should work but I suspect it may not be that easy to bleed the air out so while you are messing with pipe fittings fit a bleed point. If you have a separate header tank above the top coil connection you could T a small bore hose into the feed from the header tank that runs from the high point on the calorifier circuit but a bleed point is probably easier.

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6 minutes ago, Tony Brooks said:

Hot water into the TOP of the  coil will encourage thermo-syphoning when cold. One cure worth a try is to reverse the flow through the coil as Tracy said - hot into the bottom of the coil and cold out the top.

Oh, more efficient AND less chance of thermosiphoning. It makes me wonder why the manufacturer would state that the hot should enter at the top and why my calorifier is that way around. I'll experiment - using flexible hoses means it's quite easy to switch over if I need to.

 

12 minutes ago, Tony Brooks said:

I suspect it may not be that easy to bleed the air out so while you are messing with pipe fittings fit a bleed point. If you have a separate header tank above the top coil connection you could T a small bore hose into the feed from the header tank that runs from the high point on the calorifier circuit but a bleed point is probably easier.

I don't have any other header tank other than the engine's water input.

 

This is actually my biggest concern because where the calorifier is now, the coil is around the same height as the engine. Where I mount the new one in the engine bay, the coil is significantly higher. I'd be relying on the engine's water pump to push the water into the calorifier.

 

Can you recommend what I should use for a bleed valve? Or what I should search for? Most of what I can find online screws into a radiator...

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Valliant, producers of domestic boilers, have/had an "automatiuc air vent" on their sealed system combi boilers.

Don't know how it works but it is good for two & half bar pressure. My domestic boiler, a "VCW sine 18" is getting a bit long in the tooth but still working so I don't know if later models use something like it but Valliant are pretty good for spares.

 

Might be worth a look?

 

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1 hour ago, ivan&alice said:

Oh, more efficient AND less chance of thermosiphoning. It makes me wonder why the manufacturer would state that the hot should enter at the top and why my calorifier is that way around. I'll experiment - using flexible hoses means it's quite easy to switch over if I need to.

 

I don't have any other header tank other than the engine's water input.

 

This is actually my biggest concern because where the calorifier is now, the coil is around the same height as the engine. Where I mount the new one in the engine bay, the coil is significantly higher. I'd be relying on the engine's water pump to push the water into the calorifier.

 

Can you recommend what I should use for a bleed valve? Or what I should search for? Most of what I can find online screws into a radiator...

The bleed point needs to go at the highest point in the pipe runs so potentially at the top coil connection which is where any air will collect. It is likely that one circulation stars you will also have assistance from thermo-syphon.

 

 Although I would use a metal valve like this https://www.amazon.co.uk/Bleed-Valve-Pressure-Electric-Accessories/dp/B07CQFMKG4

the one @system 4-50 linked to would do.

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I use a lot of these   https://www.screwfix.com/p/end-feed-air-vent-cap-15mm/52451?kpid=52451&ds_kid=92700055281954514&ds_rl=1249404&gclid=Cj0KCQjw2or8BRCNARIsAC_ppyYHp3ELzh2dsDy6xwSFBHKlXCwqHbWeJRsPHWOUD2pqvNGrIrT3bB4aAky5EALw_wcB&gclsrc=aw.ds

 

Fit in a compression or solder tee.  Inexpensive.

With flow into lower connection you will not get thermosyphon cooling when the engine is shut down and I reckon it will not need a bleed in the top, the engine pump is pretty good at pushing air out providing it has water around its impeller all the time.

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10 minutes ago, system 4-50 said:

Any good? Maybe different size?

Bleeder

Ah thank you! Yes this looks right - although the largest is 19mm OD, not sure if I can jubilee it tight enough to make a seal with 22mm hose. Perhaps I should just use 16mm ID hose with the 16mm bleed valve, and then a 15mm/22mm push fit reducer on the calorifier inputs

 

4 minutes ago, Tony Brooks said:

But I don't understand - what does this screw in to? How do I install this into the line?

 

 

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1 minute ago, ivan&alice said:

Ah thank you! Yes this looks right - although the largest is 19mm OD, not sure if I can jubilee it tight enough to make a seal with 22mm hose. Perhaps I should just use 16mm ID hose with the 16mm bleed valve, and then a 15mm/22mm push fit reducer on the calorifier inputs

 

But I don't understand - what does this screw in to? How do I install this into the line?

 

 

Its 1/8" BSP to screw into a tee or a bush,,,,,, hell of a price.

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1 minute ago, ivan&alice said:

Ah thank you! Yes this looks right - although the largest is 19mm OD, not sure if I can jubilee it tight enough to make a seal with 22mm hose. Perhaps I should just use 16mm ID hose with the 16mm bleed valve, and then a 15mm/22mm push fit reducer on the calorifier inputs

 

But I don't understand - what does this screw in to? How do I install this into the line?

 

 

You screw a suitable brass T piece into/onto the calorifier. the pipewrk goes onto one branch and the air bleed goes onto the other. Mount the T vertically so the air colects undes the valve.

1 minute ago, Tracy D'arth said:

Its 1/8" BSP to screw into a tee or a bush,,,,,, hell of a price.

Screwfix do end feed ones cheaper.

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5 minutes ago, Tony Brooks said:

You screw a suitable brass T piece into/onto the calorifier.

Ah ok. The calorifier has compression fittings rather than BSP so I don't think I will be able to screw a tee directly onto the calorifier? But I could use a very short piece of pipe with an unequal tee, though I can't find 22mm x 22mm x 1/8" BSP.

 

Screwfix have a 22mm/22mm/15mm tee - I think I could use that with the 15mm compression end air vent you linked? Does that compression end fit into a compression leg of the tee without a pipe (i.e. replace where a pipe would go)? I can't see how it would work otherwise.

If so, that would mean pipe, tee with air vent, pipe, hose attached with jubilee clips.

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I you intend t push the hos ever plan copper pipe rather than a hose tail the don't, its likely to blow off. use a compression fitting to put an olive on the pipe and then push the pipe over the olive and clip. Leave the nut loose. Alternatively find a hose tail to fit to the T.

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I did intend that yes, as far as I can tell that's currently how the hose is attached - see pic (but I haven't dismantled it so it might be a hose tail). After a couple of hours of hunting I think I have found everything I need to take all the above advice. (note that I can't find a suitable 22mm hose tail so I've changed to a 13mm ID hose)

 

Flow from engine:

  1. 15mm OD engine pipe outlet
  2. 13mm ID car radiator hose (about 0.5m long)
  3. 13mm hose to 15mm pipe hose tail compression fitting (this is nickel plated brass - is that OK fpr electrolysis?)
  4. 15mm PVC pipe with compression inserts (<10cm long piece)
  5. 15mm to 22mm reducing elbow
  6. 22mm PVC pipe with compression inserts (<10cm long piece)
  7. Calorifier bottom compression fitting
  8. Calorifier top compression fitting
  9. 22mm pipe with compression inserts (<10cm long piece)
  10. 22/15/15 unequal tee with a olive-replacing air vent in the top 15mm compression
  11. 15mm PVC pipe with compression inserts (<10cm long piece)
  12. 15mm pipe to 13mm hose tail (another one)
  13. 13mm ID hose (about 1.5m long)

Back to engine

 

Please can I ask you to check my circuit?

 

This is the current outlet:

 

EngineOutlet.jpg.e93c1d5a885294ca74bceef3582b84b1.jpg

 

 

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