Heat pump

[organize4u]

Hi all,

I have a 2008 Roadtrek 190 Popular. When I was given the tour of my van, I was told to use the heat pump to "take the chill out of the air". Do I need to have the propane turned on for this feature to work because right now it just blows cold air?

Thanks,
Marie

[RAA357]

No you do not need the propane turned on. Just turn on the heat pump, make sure the thermostat is set higher then the outside air temp. My Cool Cat unit usually takes about 30-45 seconds for the heat to start coming out. I have never used my propane heater except to check it out and make sure it works every year. You may want to check and clean or replace the air filter also.

[Doneworking]

I love the heat pump feature in our Roadtrek. It works like any heat pump and is essentially air conditioning in reverse. Research heat pumps generically online and you will get an idea of how they all work.

In a 190 or 210 that propane furnace will get the whole inside warm as toast in a couple of minutes. The heat pump will be slower and they are not effective if the temps are really low.

By the way, the LP tanks on Roadtreks of the 2007 and years around that date are 10 gallon tanks and that is close to the size in most Class Cs if you look at the specs. The propane in a Roadtrek will run a heater for a long, long time.

[organize4u]

Thank you both.

Marie

[avanti]

So, I know the principle of heat pumps and I understand their theoretical advantages. But I have always wondered about their practicality. Since they have never taken over the world, I infer that they only work well in certain specific situations. Are RVs one of those situations? I.e., do they actually heat a van using less energy than a conventional electric heat strip built into most A/Cs?

[Buc22]

I use my heat pump to take chill off as my Alde Hydronic heater (propane/electric) takes about 15min to heat up. While traveling I just leave the Alde on electric the whole trip and then have no need to use heat pump.

[hbn7hj]

The Roadtrek Coolcat requires ambient temperature to be above 40F to put heat inside. Personally I never use it. I rarely have AC and the furnace works so well.

[peteco]

I have used the CoolCat heatpump just a few times when at a commercial campground with electricity in cold weather. More often I just use a little box electric heater. When the CoolCat dies I will replace with an AC only. Will be a lot cheaper and probably more reliable. THere is some added complexity to the heatpump (reversing valve and associated controls) that you eliminate when going to an AC only unit.

[tarp]

I've used the heat pump once or twice. I am plugged in so I run an electric heater and totally got rid of the propane tank. I don't require hot water or indoor gas cooking. Getting those out also- and I prefer electric.

[Kurt Franz]

I have used the heat pump quite a few times when the temps got into the 40s /50s. Turned it on in the morning and in about 10 mins it starts blowing some nice heat and warmed up the van nicely. I like the fact that I am using the stuff that the van came with and there is no additional clutter. Also, thermostat is in the bedroom!

[SeabeckStan]

Originally Posted by avanti

So, I know the principle of heat pumps and I understand their theoretical advantages. But I have always wondered about their practicality. Since they have never taken over the world, I infer that they only work well in certain specific situations. Are RVs one of those situations? I.e., do they actually heat a van using less energy than a conventional electric heat strip built into most A/Cs?

So I'm wondering where you live. If it's in the part of the country that that regularly gets sub-zero (F) in the winter, then you probably don't see many heat pumps around. But here in western Washington where it is more temperate heat pumps for homes are common. We are now living in out third home that has a heat pump as it's furnace, and believe me, it is WAY more economical that electric resistance, propane, or oil. And the way natural gas prices have been rising it's probably cheaper than that, too. The only problem is that they aren't very effective below 20 degrees (F).

Also, they are fully reversable, meaning in the heat of summer they operate as a whole-house air conditioner (cooler). A heat pump in an RV - as opposed to an air conditioner with a heat strip - is more expensive up front but certainly a practical alternative.

So ina nutshell, their use is way beyond "theoretical"!

[Luv2Go]

I've used heat pumps in RV's quite a bit, especially when in warmer climates. The one in the RT is less useful below 40F as it has no defrost function. But we still use it. Still much cheaper to run than propane, at least in our neck of the woods.

[otr]

heat pumps are actually taking over the world!
1/4 the cost to heat a house compared to resistance base board, and with current pricing about 1/3 less than our propane boiler and about 2/3 less than fuel oil. They are similar in cost to natural gas, and depending upon the electricity source have a much lower carbon footprint!

As you travel the world you will see mini split units everywhere for heating and cooling!
Here is an online calculator from Efficiency Maine to get an idea!

https://www.efficiencymaine.com/at-h...st-comparison/

[booster]

Originally Posted by otr

heat pumps are actually taking over the world!
1/4 the cost to heat a house compared to resistance base board, and with current pricing about 1/3 less than our propane boiler and about 2/3 less than fuel oil. They are similar in cost to natural gas, and depending upon the electricity source have a much lower carbon footprint!

As you travel the world you will see mini split units everywhere for heating and cooling!
Here is an online calculator from Efficiency Maine to get an idea!

https://www.efficiencymaine.com/at-h...st-comparison/

I think that you are exaggerating the benefits by expanding the definitions.


As I mentioned earlier, ground source (geothermal) are very efficient and beat almost everything else. Air source ones, not so much and if it gets really cold they need backup.


The link provided backs up exactly what I said. Geothermal great, air source similar or worse than natural gas central heat.


Since it is impractical (impossible?) to have ground source heat pumps in RVs and you need backup if you are in very cold areas, the benefits are not all the great.


If I were young enough to reap the benefits of it over time, I probably would have gone for the ground source heat pump setup when we needed a recent upgrade in our gas furnace, but the payback compared to a 96% gas furnace was nearly longer than the lifespan of either unit at 20+ years, most because of the ground source high installation costs.


Here is a link that explains the backup heat need, and this is in Atlanta, so you can imagine how it would be in the north.


https://www.estesair.com/blog/at-wha...ng-efficiently

[avanti]

As a caver, I totally understand the virtues of geothermal heat pumps.

My intent was to specifically ask about a comparison between an RV heat pump A/C vs. a similar A/C with a heat strip. I would be very interested to see a quantitative comparison of current consumed per BTU under various ambient conditions. I have an open mind, but would really like some actual data.

[booster]

Originally Posted by avanti

As a caver, I totally understand the virtues of geothermal heat pumps.

My intent was to specifically ask about a comparison between an RV heat pump A/C vs. a similar A/C with a heat strip. I would be very interested to see a quantitative comparison of current consumed per BTU under various ambient conditions. I have an open mind, but would really like some actual data.

I saw those kinds of numbers a long time ago when I first looked at whether or not a heat pump would be better to put in than a plain AC unit. Even if I could find them they would be very poor compared to the newer units though. As the link I provided above stated, but without data, the air source heat pumps fall behind gas and electric resistive heat quickly by 40*F. I will see if any data is available around here for current stuff. The local utilities and Universities around here do quite a bit of research on this kind of thing due to our climate.

[RT-NY]

Originally Posted by otr

1/4 the cost to heat a house compared to resistance base board

I have heard similar claims made, but, as booster said, I wonder if different types of heat pumps are being conflated. Is it possible for an air source heat pump (as opposed to one that has pipes going down into the ground) to cost less than baseboard heat (or, in an RV, a plug-in resistance heater)? Isn't the baseboard converting all of the electricity directly to heat?

[avanti]

Originally Posted by RT-NY

I have heard similar claims made, but, as booster said, I wonder if different types of heat pumps are being conflated. Is it possible for an air source heat pump (as opposed to one that has pipes going down into the ground) to cost less than baseboard heat (or, in an RV, a plug-in resistance heater)? Isn't the baseboard converting all of the electricity directly to heat?

Yes, resistance heaters are 100% efficient.
However, in theory, heat pumps provide a thermodynamic loophole. Namely, they pump ambient heat from the outside world into the heated space. So, you only use the electricity needed to run the "pump", and get the heat from the outside for "free".

Whether this buys you anything in practice is an empirical question, and depends on the delta-temperature between outside and inside as compared with the efficiency of the pump.

[RT-NY]

Thanks for that explanation, avanti!

So, it would be nice to know under what circumstances air source heat pumps can be chapter than baseboard heat, but it seems difficult to find definitive answers.