Thermostat for cocooned engine air extraction

[CanalRetentive]

I have a beta 50 cocooned engine with an extractor fan that removes the built up heat and blows it outside, it only runs when the engine is running however and the heat build up after shutdown is nothing short of silly. My plan is to place a thermostat inside so the fan will continue to blow after shutdown until the enclosure has cooled down. What would be a good temperature thermostat to choose? I'm thinking maybe 40c or 50c but not sure? Maybe 40c would be too low? Would be blowing for hours? Any opinions? Thanks

[Quattrodave]

The engine it's self can endure well over 90 degrees c, what can everything else in the cocoon endure? If it was me I think I'd be aiming for 65 to 70 degrees, I'd also be careful of the temp switch hysteresis else it would be cycling the fan on and off.  Most cars that I've seen with after run cooling fans also have electric coolant pumps to circulate the engine coolant whilst running the fan.  Can you not use some sort of 'chimney' and make use of convection to cool the engine cocoon?

Edited May 31, 2022 by Quattrodave

[CanalRetentive]

29 minutes ago, Quattrodave said:

The engine it's self can endure well over 90 degrees c, what can everything else in the cocoon endure? If it was me I think I'd be aiming for 65 to 70 degrees, I'd also be careful of the temp switch hysteresis else it would be cycling the fan on and off.  Most cars that I've seen with after run cooling fans also have electric coolant pumps to circulate the engine coolant whilst running the fan.  Can you not use some sort of 'chimney' and make use of convection to cool the engine cocoon?

Yeah no doubt the parts are designed to take it but I'll feel better with the cooling fan running for a while afterwards. Only came to mind yesterday when I noticed the engine room floor was warm and opened it up to find the engine still too hot to touch after nearly 5 hours of shutting down. Stays like an oven in there. I did think maybe a timer but thermostat seemed the easier option to wire in. If I dig out some boxes I might have a temp probe that attaches to my multimeter. I'll see how hot it gets before I make a decision.

Thanks for the suggestions 👍

 

 

[Alan de Enfield]

8 minutes ago, CanalRetentive said:

Yeah no doubt the parts are designed to take it but I'll feel better with the cooling fan running for a while afterwards. Only came to mind yesterday when I noticed the engine room floor was warm and opened it up to find the engine still too hot to touch after nearly 5 hours of shutting down. Stays like an oven in there. I did think maybe a timer but thermostat seemed the easier option to wire in. If I dig out some boxes I might have a temp probe that attaches to my multimeter. I'll see how hot it gets before I make a decision.

Thanks for the suggestions 👍

 

 

 

My engine room gets quite warm (2 x 6 cylinder, 6 litre engines) so I tend to leave the engine bilge blowers on for a while after stopping.

 

Maybe you could fit a bilge-blower on a timer into the cocoon and vent it elsewhere ?

 

Just a couple of examples (others - including caravan versions - are available)

 

3 inch In Line Blower 12V Boat Bilge Blower Cool Fan Marine Cabin Ventilation | eBay

 

White 12V Inline Marine Cabin Bilge Boat Air Extractor Fan / 145 CFM | eBay

 

Edit to add - I suppose that is not much different to what you have.

Can you not put a switched link into the power supply for your existing fan and put it on a timer ?

Edited May 31, 2022 by Alan de Enfield

[GUMPY]

Mine used to run on a pipe stat similar to this.

https://www.screwfix.ie/p/flomasta-03-26-270sx-cylinder-thermostat-230v/6803k

It wasn't connected to a pipe just in free air. You could then change the temp to suit your taste.

I took it out a while ago and now mine just runs when the ignition is on.

 

Edited May 31, 2022 by Loddon

[CanalRetentive]

20 minutes ago, Alan de Enfield said:

 

My engine room gets quite warm (2 x 6 cylinder, 6 litre engines) so I tend to leave the engine bilge blowers on for a while after stopping.

 

Maybe you could fit a bilge-blower on a timer into the cocoon and vent it elsewhere ?

 

Just a couple of examples (others - including caravan versions - are available)

 

3 inch In Line Blower 12V Boat Bilge Blower Cool Fan Marine Cabin Ventilation | eBay

 

White 12V Inline Marine Cabin Bilge Boat Air Extractor Fan / 145 CFM | eBay

 

Edit to add - I suppose that is not much different to what you have.

Can you not put a switched link into the power supply for your existing fan and put it on a timer ?

I couldn't decide if a timer or a thermostat was the better option. Still not decided but was leaning towards a thermostat because I thought it would involve less wiring. Just move the extractor fan over to a permanent live and install the thermostat inline. I guess the timer would need to be connected to both and permanent and switched to know when to turn on, never wired one up before tbh. Doesn't seem like it would be that much more hassle now I think of it.
 

 

16 minutes ago, Loddon said:

Mine used to run on a pipe stat similar to this.

https://www.screwfix.ie/p/flomasta-03-26-270sx-cylinder-thermostat-230v/6803k

It wasn't connected to a pipe just in free air. You could then change the temp to suit your taste.

I took it out a while ago and now mine just runs when the ignition is on.

 

Interesting, I was original looking at fixed temp thermostats but that seems like a very versatile option.

So timer or thermostat. I'll have to make a coffee and have a think 😁

[Mike Tee]

At least with a timer it wouldn't cycle plus you wouldn't forget it and end up with flat batteries on a particularly warm day!

[CanalRetentive]

5 hours ago, Mike Tee said:

At least with a timer it wouldn't cycle plus you wouldn't forget it and end up with flat batteries on a particularly warm day!

Yeah I've settled for a timer for this reason, just seems the more 'professional' solution. Something like this maybe https://www.altecautomotive.co.uk/timer-relay-fully-adjustable-12-volt--------braltt40205-1-09brbr-1614-p.asp

 

Still amazed at the price, thought a timer would be in the £5 range but I've found nothing after a long search. 😑

[Alan de Enfield]

22 minutes ago, CanalRetentive said:

Yeah I've settled for a timer for this reason, just seems the more 'professional' solution. Something like this maybe https://www.altecautomotive.co.uk/timer-relay-fully-adjustable-12-volt--------braltt40205-1-09brbr-1614-p.asp

 

Still amazed at the price, thought a timer would be in the £5 range but I've found nothing after a long search. 😑

 

 

 

[Tracy D'arth]

10 minutes ago, Alan de Enfield said:

 

 

 

How about one of these?

 

https://www.ebay.co.uk/itm/153778686649?hash=item23cdec8ab9:g:8L8AAOSwFwNeB-yo

[CanalRetentive]

1 hour ago, Tracy D'arth said:

How about one of these?

 

https://www.ebay.co.uk/itm/153778686649?hash=item23cdec8ab9:g:8L8AAOSwFwNeB-yo

That seems more like it, thanks 👍

Edit: On closer inspection unfortunately that timer is an on delay only, so the hunt for a more reasonably priced off delay timer continues! 😂

Edited May 31, 2022 by CanalRetentive

[David Mack]

This?

https://www.ebay.co.uk/itm/195061227704