Sabb 2J - calorifier connection

[PaulJ]

I have a Sabb 2JHR which is about to be fitted into me boat. Skin tank cooled. Anyone got any ideas the best way to plumb in the calorifier?

I was going to run the hot 'out' directly from the thermostat into the calorifier and then from the calorifier into the top of the skin tank.

Could 'T' off the top pipe and perhaps fit a gate valve to balance it I suppose but as the water pump is a diaphragm type I wouldnt imagine there is an awful lot of flow.

[Rob 18]

Hi Paul been thinking about best way to connect the calorifier on my 2G when I fit it! the bypass circuit is the pipe under the thermostat housing which connects back to the water pump was thinking to tee into this, thermostat housing to calorifier then back to water pump not sure if this is correct though! Peter on Bullfinch may have the answer

[PaulJ]

Hi Rob,cheers for reply.Hows yours going then ? Mine is getting lifted in on Tuesday (ish) finally.

That will be three of us wondering on this same problem then!

Would have thought it makes little difference if the return from the calorifier goes to either the bypass or the inlet on the pump as they are presumably linked internally.

Was you planning on having a T on the outlet from the thermostat- one pipe to calorifier and one to skin tank ?

[by'eck]

I have a Sabb 2JHR which is about to be fitted into me boat. Skin tank cooled. Anyone got any ideas the best way to plumb in the calorifier?

I was going to run the hot 'out' directly from the thermostat into the calorifier and then from the calorifier into the top of the skin tank.

Could 'T' off the top pipe and perhaps fit a gate valve to balance it I suppose but as the water pump is a diaphragm type I wouldnt imagine there is an awful lot of flow.

 

As suggested the common and sensible way to plumb in calorifier is to hook it into the thermostat bypass circuit. That way the water starts being heated as soon as engine starts.

 

As well as heating delays in plumbing it into main circuit, there may be overheating issues with restrictions due to narrower bore pipework through calorifier. On this point, you will likely save having to use pipe reducers by doing it properly.

 

The only downside of plumbing in a calorifier is the longer engine warm up period before thermostat opens. A manual changeover valve can optionally be added in the bypass circuit or even a second lower temp thermostat. Indeed many upmarket engine installations include dual thermostats for this very reason.

[Peter-Bullfinch]

I'm going to try and post a few pictures of the existing set up on my Sabb 2G engine. Apologies for the lumpy typing...due to a serious altercation recently with an angle grinder and sanding disc whilst wearing heavy leather gloves....big mistake!

In this last picture you can just spot the two black pipes leading into the calorifier which is on the far right just out of the picture. I will try and sketch out the plumbing for my set up and post it here because it is quite unclear from the pictures which pipe is going where.

This set up is further complicated by a cooling water circuit leading from the engine into a Bowman type cooler for a Borg Warner 'Velvet Drive' gearbox which has a return to the keel tank.

Edited November 24, 2016 by Peter-Bullfinch

[Peter-Bullfinch]

[Peter-Bullfinch]

I hope I have all the waterflow arrows going in the right direction! I should also have marked on the drawing that the thermostat is on the engine front ( left hand side) in the diagram. Hope this helps you both.

[David Mack]

I hope I have all the waterflow arrows going in the right direction! I should also have marked on the drawing that the thermostat is on the engine front ( left hand side) in the diagram. Hope this helps you both.

 

I think your arrows should look like this. Otherwise you have water going into both ends of your skin tank, and none coming out...

 

[Peter-Bullfinch]

Thank you David. It's such a long time ago that we put the plumbing in! I drew the diagram in a rush so I could catch the dry weather today and clamber up on my house roof to put a new lead flashing in. The jobs have been mounting up whilst recovering from my injuries to my hands. Warning to us all.....be very wary of wearing gloves around rotating machines!

[by'eck]

Thank you David. It's such a long time ago that we put the plumbing in! I drew the diagram in a rush so I could catch the dry weather today and clamber up on my house roof to put a new lead flashing in. The jobs have been mounting up whilst recovering from my injuries to my hands. Warning to us all.....be very wary of wearing gloves around rotating machines!

 

Yes David's flow diagram is correct. The transmission cooler fits between skin tank outlet and pump inlet which also has the calorifier return T'd into it. The pump then pushes coolish water into the bottom of the engine block and hot water comes out at the top via cylinder heads, and into thermostat.

 

What is not obvious in your diagram but shown in the top picture are the two connections to the thermostat housing, with the main stat outlet going to the skin tank inlet and the bypass immediately before thermostat, feeding the calorifier. Without the bypass water flow would be completely blocked whilst thermostat remained closed!

[PaulJ]

Thanks everyone for your replies and especially to Peter for the photos and appreciate your rushing about to put them on here. Owe you a pint :-)

Was a bit worried about plumbing the calorifier into the bypass and thought increasing the warm up time probably wasnt very sensible. But its been well tried and tested on 'Bullfinch' -so decision made-thats good enough for me :-)

Cheers

Paul

[Rob 18]

Hi Paul seems like I was thinking along the right lines, although its good to have it confirmed thanks Peter,David & Bye Eck. My engines all back together now and up and running but wont be going in just yet as I am going to grit blast the boat before the engine goes in. A question for Peter really is how good is his 2G at heating the domestic water? the Sabb thermostat is 55 degrees although Sabb do list I think a 75 degree thermostat for boats fitted with a cabin heater but Sleeman and Hawken said it was no longer available. hope your engine install goes ok. Rob.

[Peter-Bullfinch]

Our water from the calorifier becomes lovely and hot with the engine heating it. We've never had a problem. The bathroom has a shower situated over a small bath and the calorifier provides plenty of hot water for two showers and washing up. This is usually after an hours running but to be honest I've never actually timed it.

[by'eck]

Hi Paul seems like I was thinking along the right lines, although its good to have it confirmed thanks Peter,David & Bye Eck. My engines all back together now and up and running but wont be going in just yet as I am going to grit blast the boat before the engine goes in. A question for Peter really is how good is his 2G at heating the domestic water? the Sabb thermostat is 55 degrees although Sabb do list I think a 75 degree thermostat for boats fitted with a cabin heater but Sleeman and Hawken said it was no longer available. hope your engine install goes ok. Rob.

 

Paul needs to check he has the higher temp thermostat fitted. If needed a suitable generic one of correct size shouldn't be too difficult to source.

 

The lower temp one will likely be fitted to engines with direct salt water cooling as in seagoing boat. Too higher temp here can cause salt to crystallise in the water passages, blocking them.

[Peter-Bullfinch]

By'eck's point about the temperature difference between the fresh water and salt water seems to be illustrated in this view of the temperature guage from a 1977 Sabb 2G which show the lower operating temp for boats in salty water.

[Rob 18]

Hi Peter & Bye Eck thanks for the replies,Peter does your engine temperature run in the higher green band indicating that you have the higher temperature thermostat. I haven't been able to get a generic thermostat seems to be an odd size plus most modern stuff runs even hotter, being a bypass type needs to be correct diameter length and temp. Rob.

[PaulJ]

 

Paul needs to check he has the higher temp thermostat fitted. If needed a suitable generic one of correct size shouldn't be too difficult to source.

 

The lower temp one will likely be fitted to engines with direct salt water cooling as in seagoing boat. Too higher temp here can cause salt to crystallise in the water passages, blocking them.

 

Good point By'eck and something which I shall check when its in and running. Engine should have the higher temp stat fitted as was originally keel cooled.Lovely clean header tank and pipework seems to confirm it has not had the salty stuff running through it :-) Edited November 25, 2016 by PaulJ

[Peter-Bullfinch]

I haven't got this type of dual fresh and salt water guage on my boat. This one belongs to my spare engine. On the boat ours has a Sabb dial which is probably an even older version with more traditional range marked in degrees. Next time I visit the boat I will look and see what the usual running temperature is. I am fairly sure ours is set up properly for fresh water use.

[Peter-Bullfinch]

https://goo.gl/photos/i5GQyTtPjDHX7ytT6

[Peter-Bullfinch]

I've had a look at a photo of the gauges on the boat and our seems to run normally at around 155 to 160 degrees Fahrenheit which would be around 70 degrees Celsius

[Peter-Bullfinch]

https://www.dropbox.com/s/ohvgg4jt4egaoxp/IMG-20160926-WA0000.jpg?dl=0

[Peter-Bullfinch]

Phew...after a number of attempts to post this picture...I think I've managed...I'm still blaming the not quite healed paws I've saddled myself with!

[Mikexx]

I don't like the idea of prolonging the warm up time of any engine, the faster it's at operating temperature the better.

 

Therefore the idea of passing hot water to a calorifier and returning cold is less than ideal. A bypass is there for good reason.

 

One idea I have considered is using a thermostatic mixing or blending valve on the return from the calorifier and keel, such that when the return temperature of the calorifier is above a threshold the return feed would switch to the keel cold return.

 

Most radiators/engines work on a 20degsC temperature between input and output so if the engine is working at 70degsC the maximum return temperature is 50, so I'm make it initially 40. To be honest 70degsC sounds low and might be in part because of the very low temperature of the efficient keel cooling.

 

This is the sort of blender I would consider:

http://www.ebay.co.uk/itm/Reliance-Underfloor-Heating-Blending-Mixing-Valve-28mm-Heatguard-/261406633824

 

Not cheap I have to admit, but there might be others and may solve all your problems. I would think 28mm would be sufficient, anything larger becomes prohibitively expensive. 2 x 22mm would give almost the same impedance/flow rate.

 

Just an idea.

 

[PaulJ]

Thats an interesting alternative Mikexx. That would also give you the option of fine tuning it too- just a shame about the price on that one :-D

Sabb actually has tiny pipework- its all 12mm od. You can see it clearly in this pic

Edited November 28, 2016 by PaulJ

[Mikexx]

It is something I'm considering.

 

There are 22mm versions for about 1/2 the price which have the wider control range intended for underfloor heating. The types designed for hot water supplies tend to have a more limited range, with a max temp of 46C. Underfloor varieties are generally up to 65C.

 

I'm genuinely surprised about the small pipes. Flow rates are a function of the diameter^3, where twice the internal diameter gives 8 times the flow for the same pressure difference.

 

12mm OD implies very little flow!