Cruisair AC

[medsailor1]

Our Cruisair AC unit works fine in cold but on heat it just blow Luke warm air ,
Has any one got any suggestion what the problem could be ?

[Auspicious]

That's how heat pumps work. High volume, low temperature differential.

[a64pilot]

Originally Posted by medsailor1

Our Cruisair AC unit works fine in cold but on heat it just blow Luke warm air ,
Has any one got any suggestion what the problem could be ?

I have two Webasto’s, a 6K and a 16K.
The 16K of course blows a lot more air, but in heat mode it’s like a furnace, I mean seriously hot air.
The 6K blows so little heat it’s hard to believe it’s working, the reversing valve gets hot, but the air doesn’t.

They both work well in Cooling, the 16K does get colder though.

I’ve thought partially stuck reversing valve, but I don’t think that’s it.
I’m not sure what it is. I would think it normal if the 16K didn’t blow hot air like a furnace. The 16K does not have resistance heating, nor the 6K either.

[S/V Illusion]

What’s the temperature of the sea water from which you are trying to draw heat?

[Sailmonkey]

Originally Posted by a64pilot

The 6K blows so little heat it’s hard to believe it’s working, the reversing valve gets hot, but the air doesn’t.
.

Our 6k Webasto also is anemic in the heat department. I usually end up severely restricting the airflow to get the air hot. It blows great heat when the water is summer warm, but struggles as the winter wears on.

[SV Melody]

I have a pair of Cruisairs and we just got our first little cool snap over the past few days. It took awhile to flip through the little manual to determine how exactly to activate the heating function - the controller has to see a difference of at least 4 degrees F between commanded temp and current temp before it switches from cool to heat. I usually keep the boat in the low 70s inside so I either have to wait until inside temp gets in the mid 60s or I turn it up to 76 just to trigger the switch then back down to 72 or whatever. In the morning, I set it to 66 to switch back to cool then reset to my normal range. It seems to work so-so, enough to keep me and the birdies from freezing at night but I wouldn't call it a furnace . For the furnace effect, I just turn on both stove burners to high and redirect my salon fan to circulate that. 5 minutes and it's a sauna in here with that approach.

[medsailor1]

Originally Posted by Auspicious

That's how heat pumps work. High volume, low temperature differential.

Thanks but not much help

[medsailor1]

Originally Posted by S/V Illusion

What’s the temperature of the sea water from which you are trying to draw heat?

It's about 19c

[medsailor1]

Originally Posted by SV Melody

I have a pair of Cruisairs and we just got our first little cool snap over the past few days. It took awhile to flip through the little manual to determine how exactly to activate the heating function - the controller has to see a difference of at least 4 degrees F between commanded temp and current temp before it switches from cool to heat. I usually keep the boat in the low 70s inside so I either have to wait until inside temp gets in the mid 60s or I turn it up to 76 just to trigger the switch then back down to 72 or whatever. In the morning, I set it to 66 to switch back to cool then reset to my normal range. It seems to work so-so, enough to keep me and the birdies from freezing at night but I wouldn't call it a furnace . For the furnace effect, I just turn on both stove burners to high and redirect my salon fan to circulate that. 5 minutes and it's a sauna in here with that approach.

Mine wasn't hot hot last winter but it did throw out hot air , this is it's very Luke warm if you can call it that , the valve must be switching over as there is. Bit of warm air coming out .

[medsailor1]

Originally Posted by SV Melody

I have a pair of Cruisairs and we just got our first little cool snap over the past few days. It took awhile to flip through the little manual to determine how exactly to activate the heating function - the controller has to see a difference of at least 4 degrees F between commanded temp and current temp before it switches from cool to heat. I usually keep the boat in the low 70s inside so I either have to wait until inside temp gets in the mid 60s or I turn it up to 76 just to trigger the switch then back down to 72 or whatever. In the morning, I set it to 66 to switch back to cool then reset to my normal range. It seems to work so-so, enough to keep me and the birdies from freezing at night but I wouldn't call it a furnace . For the furnace effect, I just turn on both stove burners to high and redirect my salon fan to circulate that. 5 minutes and it's a sauna in here with that approach.

If I turn mine up to the high setting it still doesn't do much

[a64pilot]

Originally Posted by medsailor1

If I turn mine up to the high setting it still doesn't do much

Every Marine AC I’ve ever seen the compressor is on or off, the settings refer to fan speed, they don’t add any more cooling or heating just blow more air.
A car AC is the same

[a64pilot]

Originally Posted by medsailor1

Thanks but not much help

But he is correct, many people who come down South after living their lives up North and having furnaces, hate the heat pumps we have down here, because they don’t feel the heat coming out of the registers like they did with their oil fired furnaces. Heat pumps move a lot of air warmed just a little compared to a furnace that moves much less air, but it’s HOT air.

Heat pumps do just that, they move heat. In AC mode they pump heat out of the boat, in heating mode they remove heat from the water and pump it into the boat, when the water is cold, there isn’t much heat to pump though, so the colder the water gets, The less effective the heat pump is. So the colder it gets, the more heat you need, the less heat you have, reason why you don’t see so many heat pumps up North.
Home heat pumps usually have heating elements called heat strips for when it’s too cold for the heat pump to work well, not many boat heat pumps do though.

[medsailor1]

Originally Posted by a64pilot

But he is correct, many people who come down South after living their lives up North and having furnaces, hate the heat pumps we have down here, because they don’t feel the heat coming out of the registers like they did with their oil fired furnaces. Heat pumps move a lot of air warmed just a little compared to a furnace that moves much less air, but it’s HOT air.

Heat pumps do just that, they move heat. In AC mode they pump heat out of the boat, in heating mode they remove heat from the water and pump it into the boat, when the water is cold, there isn’t much heat to pump though, so the colder the water gets, The less effective the heat pump is. So the colder it gets, the more heat you need, the less heat you have, reason why you don’t see so many heat pumps up North.
Home heat pumps usually have heating elements called heat strips for when it’s too cold for the heat pump to work well, not many boat heat pumps do though.

Thanks I understand all that but the sea water is around 19/20c which isn't that cold plus last time we used it the sea temp was colder and we got hot air out so much that you couldn't stand next to it for long .
So in this case it has nothing to do with the temp of the water .

[Auspicious]

Originally Posted by a64pilot

Home heat pumps usually have heating elements called heat strips for when it’s too cold for the heat pump to work well, not many boat heat pumps do though.

True. Electric bills soar when the little red "emergency heat" light comes on. Heat pumps can be set up to use nearly anything including radiant heat, natural gas, or oil to back up the heat pump.

Originally Posted by medsailor1

Thanks I understand all that but the sea water is around 19/20c which isn't that cold plus last time we used it the sea temp was colder and we got hot air out so much that you couldn't stand next to it for long .
So in this case it has nothing to do with the temp of the water .

I have seen marine heat pumps with resistive heat as a backup. Could that have been the case? I've never experienced a heat pump that circulated air "you couldn't stand next to." That is very odd.

[a64pilot]

Originally Posted by Auspicious

True. Electric bills soar when the little red "emergency heat" light comes on. Heat pumps can be set up to use nearly anything including radiant heat, natural gas, or oil to back up the heat pump.







I have seen marine heat pumps with resistive heat as a backup. Could that have been the case? I've never experienced a heat pump that circulated air "you couldn't stand next to." That is very odd.

Actually believe it or not but my 16K Webasto gets stinking hot.
We have a cold snap coming tonight, I’ll try to remember to measure it tomorrow, but I bet it’s over 100F, with say a 70 intake air.
It does not have resistance heat.