How many GPM for a heater?

[coldwater-echelon]

I've got a 4 port heater which has the larger coil in it. I would like to add a circulation pump to help with heat at idle and also provide heat when the motor is off. I see Bakes has a 3 gpm pump and a 4 and a 5 gpm magdrive pump. My question is how much flow does the coil need? If there a thing as too much flow?

Thanks

[05hammerhead]

This is what I bought and it works perfect.

https://www.amazon.com/gp/product/B0073JNWZ6/ref=oh_aui_search_detailpage?ie=UTF8&psc=1

[granddaddy55]

Mounted where in the system?  

Really will work with pump wired to heater switch with no engine running?  Wouldn’t it eventually pull cold water outside into heater core ?  I’m sure it’s an improvement  at idle 

[BlackBluMalibu]

Yes, Will keep cabin area 10-15 degrees warmer than outside air. When engine off it will only keep it this way for about 15 minutes and then the air coming out begins to cool and by 30 minutes it’s is luke warm. I have two 3 Port 300s, one under observer seat and the second under the starboard corner seat. From engine outlet it runs to observer and then back to engine compartment and across to #2 and then I installed the pump after #2 heater and back to engine inlet.  Mine is separate switch, so I don’t turn the pump on until after the engine is warm for the first start of the day. Once running and at temperature, all 6 pull outs put out great heat.    We go pretty much year round wakeboarding and wakesurfing in Virginia. That’s why we also put average of 350 hours a year on our boats. lol. Heaters are great for late fall, winter and early spring!

Edited October 4, 2018 by BlackBluMalibu

[Nitrousbird]

Anyone know how well these helper pumps work with a partial closed cooling setup?  I'd love to have the heater work with the motor off...on it isn't necessary at all. 

[justgary]

27 minutes ago, Nitrousbird said:

Anyone know how well these helper pumps work with a partial closed cooling setup?  I'd love to have the heater work with the motor off...on it isn't necessary at all. 

I don't have a pump, but it should work great with closed cooling.  Plenty of heat stored in that coolant just waiting for you to put it to use.