Aquathot Questions for a Noob

[metalfarm]

2021 Discovery.


We live in Florida so we're using heat for first time and I don't quite understand. I guess I expected it to blow out of the vents on the ceiling like the AC. I can hear the heat but I can't feel it. Here are my questions thanks for looking!



1. Where is the heat coming out of?


2. Is Electric Aquahot good enough if it's over 45-50 degrees

3. When is the diesel Aquahot necessary?



3. Does the heated floor work on electric or is it diesel only?


4. How does engine preheat work/How do I set the thermostat if I need heat in the back for the kids while driving?





Thanks!

[TampaDave]

I have an older unit so your experience will be a little different from mine -- here's what I can say

1. Note, the aquahot can either deliver hot water, or heat your rig, but it can't do both at the same time. Any time water is running -- even a little bit -- the heater will shut off.
2. I haven't had much luck heating with electric. On my old rig, electric is enough for a quick shower and that's about it. It's only really helpful if the diesel burner is down. The newer units have much better AC elements so ymmv
3. But, run the diesel. Those things clog up if you don't run them regularly.
4. Far as heating is concerned, my unit works fantastic. We spent an entire winter in Utah and were comfortable down into the upper teens.
5. That said, it can be finicky in really cold weather. Your best bet when it gets below freezing is to unhook from city water, use your tanks and turn your fresh water pump off when you aren't using it. Long as you keep the basement fairly warm it should work.
6. Once again, you need to run the heater from time to time, otherwise valves get stuck and the thing generally quits working. So run it whenever you get the chance, forget about those noisy heat pumps. If you don't camp in the winter, run the heater for a few minutes once a month even in the summer just to keep it in shape.
7. Do the annual maintenance. Just do it. Among other things, that's a good first step any time the AH decides not to work.

OK, to turn the heater on --

1. Make sure there's no water running, hot or cold. All faucets off.
2. Get the AH up to operating temperature. Takes about two minutes with the diesel burner and all day with the electric element, just saying.
3. Set your thermostat substantially above ambient, 10 degrees if you have to. Crank that sucker up.
4. Enjoy.

I don't know where your heat comes out, mine comes out of registers along the floor. Each one has a little fan behind it that I can clearly hear when it turns on. Dunno how it works, or even how to tell if it's working, if you have radiant floor heating.

You should have a zone thermostat. It probably says "gas" when it means "aquahot." So, choose gas, choose zone, set temp, no more popsickle kids or cats (you think your kids are particular, try traveling with a cat). Works at the trailer park or underway. Cool thing about being on the move is, engine coolant circulates through the AH and in mild temperatures, that may be enough to heat the rig. Once it gets colder, like in the 30's, engine heat isn't enough and you have to light up the diesel burner. Which is fine, just don't forget to shut it off when you go to refuel.

You should have a third zone in the basement, on mine there's a thermostat dial down there, I don't know where yours is. Crank that sucker all the way up. All the way.

I would recommend running engine pre-heat for 20 minutes or so when it's below about 55 degrees out, diesels tend to draw a lot of electricity when it's cold, there's less drama starting out if you use it. Don't forget to turn it off.

-------------

If your heater truly honestly isn't working:

1. Make sure there's no water running. Even a leaky faucet can throw it off under some conditions.
2. Make sure unit is at operating temperature (does the burner come on?)
3. Check the control panel and see if it's showing a burner fault. If you have an actual physical switch to turn the diesel burner on, it should be glowing green. If the switch is on, but it's not green, you have a burner fault. If yours is run by a computer, I'm not sure what to tell you, might have to dig out the manual
3a. If there's' a burner fault, do annual maintenance
3b. If not, rummage around in the basement, and find the aquahot unit, and look at the LED lights. First, look and see if any are red. If not, write down which ones are on and which ones are off. Let us know what you find.

Walk before you run. Let's see if it works with the diesel burner first before we start working the AC side of things.

[Bobby Dowdle]

Electric on the aqua hot is to use the sinks for hot water.
Diesel is for heating the coach. You can run both together to give best performance.
The floor heat needs to run off diesel or both diesel and electric.
The preheat will be using diesel or both diesel and electric because the temps will be so low outside.
As far as blowing out of the roof vents. That’s only for the heat pump. All aqua hot heat comes from the floor vents.

[dizcom]

1 - the floor vents. The AquaHot will run for a bit before it starts to blow any air.


2 - no. The electric side is fairly weak and isn't really meant to heat your coach.


3 - For heat, always, whether furnace or floor. For hot water, most of the time. We find that in warmer weather the electric side is fine for producing enough hot water for our purposes, including showers. In the cold though, it won't be adequate.


4 - Turn it on a couple hours before you go. You generally won't need it unless it's gotten very cold though. 40 to 50, you don't need it and it won't help.



For heat underway, it's fine to run the AquaHot and turn the heat up using the coach thermostat. If it's been cold and you haven't been in it, you'll want to turn it on a couple hours before you drive. If you start the AquaHot and try to drive away immediately, it will be some time before it starts producing enough heat to heat the coach. The dash heat isn't enough to heat the whole coach, so if there's anyone riding in back you'll want the furnace running.

[n2zon]

You didn't say which model AH you have.

For us, with our 450D, the electric element provides adequate heat down to about 50F. Colder than that and we need to use the heat pumps (down to 40-45) or the diesel burner (if it's colder). We much prefer the electric element to the heat pumps--it's quiet!

As others have said, there are floor-level vents for the heat exchanger fans to blow out of.

If you have an engine loop (aka "motoraid"), you will not need to turn on the burner when you're under way. The engine will provide plenty of heat for the AH heat exchangers without burning more diesel in the AH. Set the thermostat for Furnace in both zones.

If you have a 450D, the electric element will support a "Navy shower." Get wet, get soapy, rinse. But the luxury of plenty of hot water for a long shower with full hookups requires you to run the AH burner.

HTH,

John

[hilgert]

metalfarm, we probably have a similar setup to yours, and we are also in Florida (Space Coast, which is our home base).

We've had our Discovery all over the US, in hot weather (Florida and Texas summers) and cold weather (Ohio, Idaho and Colorado winters)...the Aqua-Hot has been amazing:

• Delivers both hot water and heat at the same time (see note below).
• Delivers continuous hot water on electric-only until the incoming water temperature drops below 70°F; below that it's more like a propane hot water heater (5-10 minutes only in shower).
• Most months in Florida we run electric-only unless we take back-to-back showers (we both like long showers), or we need heat in the coach.
• When heating the coach we use diesel plus electric (the electric is never off when on shore power). Electric-only would be a stretch.
• Heat comes out of "cozy heat exchangers" (look like normal registers) on the walls near the floor. We have one-each next to the driver and passenger seats, one in the galley, one in the 1/2 bath, one in the rear bath and two under the bed.
• Our floor heat is from electric heating pads beneath the tile, not from the Aqua-Hot.
• Note: Coach heat will *normally* shut off if you run hot water (it's called "hot water priority" or something). I defeated this by shorting the wires on the incoming sensor (incoming cold water to the Aqua-Hot) so the unit does not disable heat when cold water enters. Now we have both hot water *and* heat at the same time, even when it's freezing outside.
• We've used this setup in below-freezing weather (many nights down to 0°F) when we wintered in Ohio a couple of years ago...stayed nice and toasty inside, even when running hot water.

[TampaDave]

Originally Posted by hilgert

metalfarm, [*]Note: Coach heat will *normally* shut off if you run hot water (it's called "hot water priority" or something). I defeated this by shorting the wires on the incoming sensor (incoming cold water to the Aqua-Hot) so the unit does not disable heat when cold water enters. Now we have both hot water *and* heat at the same time, even when it's freezing outside.

Brilliant!

That cold-water bypass has been an endless source of frustration, can't tell you how many times we woke up freezing at 4am because that doggone thing got itself stuck in hot-water-heater mode in the middle of the night.

I can kinda see where they are coming from, it's easy to outrun the hot water supply at least with the older units. Easy enough to solve that problem by running off the internal tank in cold weather. That bypass is more trouble than it's worth, it seems.

Thanks for the tip! Two enthusiastic thumbs up for that.

[DuaneMiller]

Originally Posted by metalfarm

2021 Discovery.


We live in Florida so we're using heat for first time and I don't quite understand. I guess I expected it to blow out of the vents on the ceiling like the AC. I can hear the heat but I can't feel it. Here are my questions thanks for looking!



1. Where is the heat coming out of?


2. Is Electric Aquahot good enough if it's over 45-50 degrees

3. When is the diesel Aquahot necessary?



3. Does the heated floor work on electric or is it diesel only?


4. How does engine preheat work/How do I set the thermostat if I need heat in the back for the kids while driving?





Thanks!

You've asked a lot of questions... In order for us to provide specific answers, can you tell us which model Discovery you have?

[Porkypine73]

Note: Coach heat will *normally* shut off if you run hot water (it's called "hot water priority" or something). I defeated this by shorting the wires on the incoming sensor (incoming cold water to the Aqua-Hot) so the unit does not disable heat when cold water enters. Now we have both hot water *and* heat at the same time, even when it's freezing outside.[*]We've used this setup in below-freezing weather (many nights down to 0°F) when we wintered in Ohio a couple of years ago...stayed nice and toasty inside, even when running hot water.


Could you please explain in detail on how you bypassed this are you referring to the low temperature thermostat or did you do it at the board I had to replace my board and since then we don’t have heat while using hot water
I would like to return to having both at the same time thanks