Heater not that hot

[duffymahoney]

Hello everyone,

My heater craft heater has never been that hot, and I am looking to make it more hot if possible. My lake is cold/ air temps I have my hot water coming off the intake manifold location (I believe stock location) then it runs kink free to the heater core, then out to the raw water intake via a Y fitting (low idle) that heatercraft sells. The hot water into the core is hot, but out is colder, like it should be, but only warm air comes out. If I leave the heater off for say 5 minutes or so, then turn the heater on, its much hotter, but slowly gets colder. My engine temp runs pretty hot with my current thermostat of 185.

Would it be hotter if I had it recirculating through just the hot side of the thermostat? Like out of the intake and into the motor water pump? So it never really gets cold?


The Y strainer, has a small hole in it on the Y side, I assume that's to slow the exit of hot water from the engine? Could I drill it out more? Any ideas?!!

[Dandy]

Have you contacted HeaterCraft? I am willing to bet they could help.

I see that they offer systems with a recirculating pump such as in the link below:
http://www.heatercraft.com/marine-he...-with-harness/

I am guessing that this helps to keep the temp up, not sure what the circulation loop is.

I have been curious about this as well since our boat does not have a heater and I am intending to install one. Being in MN, the spring and fall temps require a heater if I want my wife to drive for me.

[duffymahoney]

Their phone seems to not work. I have tried calling a bunch.

I wouldn't think you would need an inline pump, since a marine heater is the same principle as a car heater.

[hcooperrn]

I think it's the distance that is different between marine and auto, right? My previous 22v did not have a circulator, however, my Z3 does, and there's a noticeable difference in how quickly warm air starts coming out of the vents. I'm sure the closed system helps a bit as well, though it does cool down quickly after shutting the engine off.

In your case, it sounds like the heater core just isn't getting enough heat to keep the coils warm -- with the fan off, there is no cooling effect on them, so they retain the heat, kick the fan on, and they can't rewarm enough, if I'm reading your description correctly. That to me says either not enough heat going in (needs more hot water pumped to it) or the water coming in isn't warm enough to keep up (sounds less likely given the high temp thermostat). I guess a third option is that the water is moving too fast to transfer the heat maybe?

[duffymahoney]

I think it's the distance that is different between marine and auto, right? My previous 22v did not have a circulator, however, my Z3 does, and there's a noticeable difference in how quickly warm air starts coming out of the vents. I'm sure the closed system helps a bit as well, though it does cool down quickly after shutting the engine off.

In your case, it sounds like the heater core just isn't getting enough heat to keep the coils warm -- with the fan off, there is no cooling effect on them, so they retain the heat, kick the fan on, and they can't rewarm enough, if I'm reading your description correctly. That to me says either not enough heat going in (needs more hot water pumped to it) or the water coming in isn't warm enough to keep up (sounds less likely given the high temp thermostat). I guess a third option is that the water is moving too fast to transfer the heat maybe?

Agreed, I think not enough hot water is getting to it, that's my guess at least. I think I can actually test that by removing the Y and putting a standard T in.

[JohnnieMo]

With mine (factory) I find that it is hot only as long as the boat is moving and using lots of fuel. The open looped cooling system cools off very quickly after the engine slows down. Heat only comes at surf speeds etc. Idle will not keep it hot.

[duffymahoney]

I chatted with him, he suggested checking the exit hoses to see if one slipped off, then check flow of water. You need around 3 gallons a minute. Then if I'm still not happy to put the return to the water circulation pump.

[bsreid]

What about putting on of these in the line to help it circulate the hot water better?
https://www.wakemakers.com/heater-cr...e-fitting.html

[Dandy]

I personally think this is what would be best suited to aid with this issue:
https://www.wakemakers.com/heater-cr...rofit-kit.html

[duffymahoney]

They said to try that after just trying recirculating. He said it was probably an overkill, unless I want full heat at idle.

[freeheel4life]

I never use the "y" that heatercraft sends in kits when retrofitting. Always use the barbed fittings and hook up to manifold and circ pump. Closed loops and newer pcms obviously are a bit different. If you are really wanting the heat I'm thinking moving to circ pump isn't going to satisfy you.
Inline pump will though.
Typically see same results as above have mentioned. Will make great heat under load but will dissipate quite quickly at idle even after moving return to circ pump with barbed fitting. We are down here in Boise but still cold in shoulder season and cold water temps combined make for cold post work surf sets. Are you running a two vent or a three??

[duffymahoney]

I never use the "y" that heatercraft sends in kits when retrofitting. Always use the barbed fittings and hook up to manifold and circ pump. Closed loops and newer pcms obviously are a bit different. If you are really wanting the heat I'm thinking moving to circ pump isn't going to satisfy you.
Inline pump will though.
Typically see same results as above have mentioned. Will make great heat under load but will dissipate quite quickly at idle even after moving return to circ pump with barbed fitting. We are down here in Boise but still cold in shoulder season and cold water temps combined make for cold post work surf sets. Are you running a two vent or a three??

Thanks, I think I will try drilling a larger hole in the Y first. See if I can get more water to move through it, he was pretty convinced that it was not enough flow. He said 3 gallons per minute is needed, he said a 165 thermostat should put out 135 air constantly. I am also thinking one of the vent hoses might have come lose, which would lead to lots more air then you want moving over the fins and cooling it down too much. I have a 4 port heater, and I didn't think to check the two ports under the drivers seat.

[talltigeguy]

What about putting on of these in the line to help it circulate the hot water better?
https://www.wakemakers.com/heater-cr...e-fitting.html

You need this, absolutely. But I think you are describing that you already have one? And yours has some sort of restrictor in it? Once you get one that actually lets water flow, your heater will be like the Sahara desert.

I could only imagine that the reason for a restrictor in it is to stop the hot water from recirculating too fast in the engine. But there is no way that the hot water going back into the engine will be enough to cause the engine to overheat. The one I used was this exact one above and it was just an open pipe on both ends of the Y.

I once had a dumb mechanic do me the favor of removing it. I noticed it immediately due to poor heat. I had a come apart and educated the mechanic how it works. Thankfully, he had not thrown it away, and I made him reinstall it on his own time. One more reason to do your own boat work.

[duffymahoney]

Inside the Y on the 5/8 side is a small hole, say like .25 or so, that is to increase pressure. So it's not just an open 5/8 - 1-1/4 like you would guess. Heatercraft says the low idle works in 75% of cases. If that doesn't work, he suggested going back to circ pump, if that doesn't work then put a 3 gallon per minute heatercraft pump in line to circ it from the motor to the circ pump.

He had never thought or tried to drill the .25 hole a little larger, see if I can get enough flow. Might work perfectly.

[duffymahoney]

I drilled the small hole out to 3/16 and it fixed all my issues, temp at idle of the heater is great, it's crazy hot at any speed other then that. Pretty happy with my 2 minute fix.