More Heat Pump Questions

amanda_h · 11-25-2007, 12:13 PM

I was going to post the following questions about heat pumps and then I saw David and Fran's thread and had some of my questions answered. I'm still going to post my set of questions in hopes that I can get my specific concerns answered by all of you experts! Thanks!:

I'm back with some newbie question!

I don't think we are understanding exactly how the heat pump works. When we are hooked up to shore power, 50 amps, and we set the thermostat to "electric heat," exactly what is suppose to happen?

Here's what we thought was suppose to happen because this is what happened when we first used the A/C for heat. When the heat pump starts, we heard the A/C compressor kick in just as if the A/C were being used but with warm air being blown through the ceiling ducts. At the same time we hear the propane furnace ignite and blow warm air out the floor vents. So we assume that this is the way the system is suppose to work ...both heat pump and propane furnace heating at the same time to get things warm faster than just using the propane furnace alone ...or so we assume.

However, we started noticing that the ceiling ducts would not blow at all sometimes ...just the propane furance blowing through the floor vents. We called our dealer and they told us that it sounds as if something is not working right as the ceiling fans should always be blowing when "electric heat" is chosen.

Can somebody explain to us what's happening here. Is it normal for the ceiling blowers to come on sometimes and at other times, not to come on? Do we in fact have a defect in the system somewhere? It seems like the ceiling fans come on now more than they did.

And also, what is happening outside where the furnace "outlet" is blowing hot air out into space? Is this correct? When the propane furnace is on with the switch in "electric" mode, we notice that hot air is blowing at a pretty good clip out the vent on the left side of the coach right near the battery compartment. Why is this? Is this normal? It sure seems like a waste to have such hot air blowing to the outside.

I hope I've explained this accurately ...or understandably. I sometimes use terms that I know that aren't correct but don't know what else to call them; like "vents."

Thanks!

amanda_h · 11-25-2007, 12:13 PM

I was going to post the following questions about heat pumps and then I saw David and Fran's thread and had some of my questions answered. I'm still going to post my set of questions in hopes that I can get my specific concerns answered by all of you experts! Thanks!:

I'm back with some newbie question!

I don't think we are understanding exactly how the heat pump works. When we are hooked up to shore power, 50 amps, and we set the thermostat to "electric heat," exactly what is suppose to happen?

Here's what we thought was suppose to happen because this is what happened when we first used the A/C for heat. When the heat pump starts, we heard the A/C compressor kick in just as if the A/C were being used but with warm air being blown through the ceiling ducts. At the same time we hear the propane furnace ignite and blow warm air out the floor vents. So we assume that this is the way the system is suppose to work ...both heat pump and propane furnace heating at the same time to get things warm faster than just using the propane furnace alone ...or so we assume.

However, we started noticing that the ceiling ducts would not blow at all sometimes ...just the propane furance blowing through the floor vents. We called our dealer and they told us that it sounds as if something is not working right as the ceiling fans should always be blowing when "electric heat" is chosen.

Can somebody explain to us what's happening here. Is it normal for the ceiling blowers to come on sometimes and at other times, not to come on? Do we in fact have a defect in the system somewhere? It seems like the ceiling fans come on now more than they did.

And also, what is happening outside where the furnace "outlet" is blowing hot air out into space? Is this correct? When the propane furnace is on with the switch in "electric" mode, we notice that hot air is blowing at a pretty good clip out the vent on the left side of the coach right near the battery compartment. Why is this? Is this normal? It sure seems like a waste to have such hot air blowing to the outside.

I hope I've explained this accurately ...or understandably. I sometimes use terms that I know that aren't correct but don't know what else to call them; like "vents."

Thanks!

FleetMan · 11-25-2007, 12:58 PM

Check your owners manuals. It sounds like everything is operating as they are supposed to. Depending on outside temperatures, the propane furnace will either augment the heat pump in supplying warm air to the coach or, if it is cold enough, be the primary heat source - even though you have "electric heat" selected.

The furnaces in most RVs is relatively inefficient in comparison to a high end home furnace. The hot exhaust air you experience is normal. I'd like to be able to capture it and make more efficient use of it also.

rvten · 11-25-2007, 01:02 PM

How cold is it where you are?
Heat pump is only good to 40 deg. Than the propane furnace takes mover.

When you first turned on the heat pump then temp could have been just above 40 but still too cold for just the HP to work by itself. So the furnace would kick in.

If colder than 40 propane furnace is the only thing that will work.

Trek-Cyclist · 11-25-2007, 01:09 PM

Also If you set the temp 4 degrees above what the inside temp reads the gas furnace will also kick in to help heat.. We push ours up by 3 degrees at a time... That way the LPG heater doesn't come on...

amanda_h · 11-25-2007, 02:05 PM

Oh, I knew I could count you experts to help us out!

I think our system is probably working correctly from what all of you are saying.

I'll fool around with a bit more and report back.

So all that hot exhaust coming out of the the side of the coach is normal, eh? Gee yeah, that seems like such a waste!

Also, while I'm here ...I do think that this is something we will have to have checked but I notice that no matter if the fan selector is set for "low" or "high" there isn't much difference in fan speed. I think when we first got the coach, there was a significant difference between "low" and "high" ...is that what you all experience?

Thanks again to all of you!

Trek-Cyclist · 11-25-2007, 03:50 PM

Low/High works ONLY on fan and A/C and not very much difference so I run ours on Hi all the time unless I just want to move the air around on on fan...

On heat the fan speed is preset..I think at high
Stay warm!

skigramp · 11-25-2007, 03:56 PM

amanda ...

On our coach whenever the LP furnace, Electric heatpump is running the fan runs at a single preset speed ...

The fan speed only makes a difference when I have the thermostat set on fan ...

Bill Gotthelf · 11-25-2007, 04:15 PM

Also regarding the outside heat that is the exhaust from the propane flame used to heat the coils. These coils get hot and then the interior blower blows air over them from the inside where it is heated and blown through the coach. It is not a very efficent heating system as much waste heat is lost but it is very cheap to manufactur so that is why they are in our coaches.

Jeeperrmartin · 11-25-2007, 05:32 PM

You would think on the top of the line coach they would have something different and more energy wise.

To me that add a lot of other stuff that I could do without.

SCVJeff · 11-25-2007, 08:50 PM

It's exactly like every other RV heater on the market and isn't high or low-end dependent

Amanda: I answered your PM, and it's verbatim to the answers here.

As mentioned, there is very little difference between high & low fan. The switch works in all modes: heatpump, A/C, or fan, but with the compressors running you might not hear the difference. I put my anemometer on the vent one day and measured only .5MPH between the two modes.

rvten · 11-26-2007, 03:42 AM

Had the heat pump on our Adventurer 35U and also on our new Aspect. Love it. Save a lot pf propane.

Izzyblueye · 11-26-2007, 03:43 AM

The only time I ever notice a change in air movement on the HI-Lo fan switch is when I am using "Fan" only setting. As for the hot air coming out of the furnace as exhaust. Wouldn't it be great if some one came up with a simple heat exchanger that could use this heat to augment the total heating system instead of being totally wasted.

Carle · 11-26-2007, 06:19 AM

One more consideration - Any time you 'burn' fuel, in this case propane, you have exhaust. This exhaust is what you feel coming out of the furnace on the side of your motorhome. You wouldn't want this exhaust to come into your motorhome under any circumstances any more than you would want car exhaust to come in.

Two holes are on the side of the motorhome furnace. One is the intake of fresh air for combustion and the other is for combusted or exhaust air to leave the furnace.

This is the same way your gas furnace works at home. I does seem like a waste of energy but the exhaust has to stay outside.

Carle McFarland, 2004 Journey 36G

Trek-Cyclist · 11-26-2007, 06:21 AM

On ours the HI/LOW fan ONLY works on Fan and A/C. When in Electric heat mode the fan speed is preset to HIGH even if select low. I can only guess why, maybe if it wasn't in HIGH air flow the Heat Pump could OVERHEAT...HHUUMM let me ponder that...
You can check if the fan is in HI or LOW speed by the Power Line system there is about a 1 amp difference

Izzyblueye · 11-26-2007, 07:36 AM

Carle: completely understand and agree with your post. My thoughts were, if this heat could be run over a cast iron hollow sealed pipe, i.e,(heat exchanger), with a fan in it, drawing its air from a fresh source, such as inside the coach. This exhaust heat would then be productive and increase the efficiency of the gas heat system. For my money, I would rather see them do this sort of thing than put more of those infernal mirrors and gingerbread all over the inside of the coach. Just thinking out loud. My bet is some one out there could engineer this with very little problem or cost. Propane keeps going up like all fuels.

DancinCampers · 11-26-2007, 07:48 AM

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Ed/Full-time:
When in Electric heat mode the fan speed is preset to HIGH even if select low. I can only guess why, maybe if it wasn't in HIGH air flow the Heat Pump could OVERHEAT...HHUUMM let me ponder that...
</div></BLOCKQUOTE>

In electric heat mode, both compressors always run, indoor & outdoor fans run on high. If you could select lo indoor fan speed there would be a good chance the heat would not be removed from the indoor coils enough. This would cause the pressures on the high side to increase, causing the high pressure safety to trip. This would be more evident in higher ambient temps.

Here is a link to a Quick Reference Guide on the P.C. Board/Wall Thermostat.

Quick Reference Guide

Jeeperrmartin · 11-26-2007, 09:09 AM

That is how my wife and I feel. We say what are they thinking. Especially on some of the colors the put in.

I would like to see more of these options that you would order, rather than automatically putting them on.

amanda_h · 11-26-2007, 11:10 AM

Thanks, everybody, for all the great feedback!

I'm bouncing back and forth on whether our fan switch is defective or not. Even on "fan only" I can't really tell any difference in speed or just an extremely slight difference.

Thanks, Dancincampers for the link to the RVP Quick Reference Guide. I've saved a copy of that and will try to scrutinize it when I get the chance. It has some great information.

I kind of have a hunch that when we had the dealer replace a defective fresh water tank gauge, they mis-wired the fan switch when putting the panel back together. I don't look forward to helping DH pull that thing apart and trace all the wiring to see if everything is connected to where it should be.

Thanks again!

Izzyblueye · 11-26-2007, 03:59 PM

JEEPERRMARTIN: One of the items that really gripes me on my particular coach, was the elimination of the water pump switch in the bathroom. Yet they put a radio speaker in floor by the recliner that catches dust and dirt. There is already a speaker directly overhead. Just wasted money IMHO.