Flat Plate effeciency

[carringb]

This is for the guys with flat plate heat exchangers....

What kind of heat to you get from your hot water when the coolant is at max-temp and the engine is running? Do these transfer enough heat to use as a continuous hot water heater?

I'm trying to figure out a way to get the hot tub hot fast when boondocking. The electric hot tub pump only heat the rub ~2 degrees/hour

[daveb]

Enough heat that I had to add a tempering valve. I've never measure the temp with the espar off and the engine running. I don't know why it wouldn't keep the temps up but I also have a circulation pump in the loop to increase coolant flows when the Espar is off.

[dig255]

When I bring mine, I use a Ecotemp L5 flash heater with a separate Shure Flow pump. Takes me about 4 hours to be at full operational temp 104°. Wouldn't want to idle for that long.

[carringb]

Thanks guys. I didn't even think about a gas fired heater. I'm still not sure which way to go. My pump will do 15 GPM so I suspect the flat plate will cope better with the higher flow. Also the smaller space needs are nice.

[Bbasso]

Keep in mind the flow rate, if I have my valve open on my eccotemp it's half heat compared to not being able to touch the water on low pressure.