Community Forums

Piper911 · 02-09-2025, 10:31 AM

I have a 2018 40IH Phaeton with Aquahot. Recently I read in a thread that you can drive and heat the entire coach with the furnace on (but Aquahot off).

Yesterday I tried this but was unable to heat the coach going down the road except dash heat. When I have the furnace on but the diesel or electric off I can't get any heat from the registers. The spyder control is also telling me to select a heat source (its flashing this above the heat selection). I tried with the engine preheat both on and off with no difference. I also tried Electric, but as I understand it, this is not available.

I can get heat if I use the diesel Aquahot going down the road.

Can someone help me with what configuration they use to get heat with the diesel Aquahot off?

Thanks

d23haynes57 · 02-09-2025, 10:40 AM

How long did you try? From a cold start it will take a long time for enough heat to transfer from the engine to the boiler for it to make heat. It works best if you use the burner to preheat the system and maybe even the coach. For low speed, in traffic operation the engine may not make enough heat for this to work.

garykk · 02-09-2025, 01:37 PM

You won’t get heat from the electric side unless you run the genset. As mentioned it will take a long time to get heat from the engine and even then I think you have to have the Spyder panel set to furnace to get the pumps to work. I’ve read where some folks just use the diesel side, others don’t. I’ve never had cause to use the heat while on the road but I would probably use the diesel side, can’t see any reason not to.

RangerIV · 02-09-2025, 02:20 PM

To add to GaryKK post, I have used the Aquahot to heat the coach while driving many times. If it's cold enough to need it while driving I have already had it running for the engine pre heat for aprox. 1 hr. so it's already hot. I set the Aquahot to furnace, turn off the engine pre heat, select desired temp. and drive. If the engine produces enough heat of 180 degrees or more the diesel
burner may not fire or it may fire if needed to assist in maintaining the needed temp. for it to produce heat.

jimpav · 02-10-2025, 08:13 AM

All of the above suggestions are correct however in the case of my 2023 Phaeton 40 IH, I have some of my Aquahot lines kinked underneath someplace thereby preventing hot fluid from reaching the floor registers. I’ve tried multiple times , including Red Bay, to find the kinks with the slides in, but still no heat. Everything works perfectly with the slides out when parked.

d23haynes57 · 02-10-2025, 08:19 AM

If you have lines that are kinking enough to stop flow, then they are kinking enough that at some point they will fail. Warranty correction required for sure.

garykk · 02-10-2025, 09:34 AM

Quote:

Originally Posted by d23haynes57

If you have lines that are kinking enough to stop flow, then they are kinking enough that at some point they will fail. Warranty correction required for sure.

Agree, don’t let Tiffin off the hook on this.

**NLOVNIT** · 02-10-2025, 01:55 PM

I had a 2018 Phaeton 40IH. If your coach is all electric, as mine was, then posts above are correct.
1. You are not going to get the heat pumps to run unless you run your generator ( & it has to be above 40 to get them to even put out heat).
2. You won't get the furnace to run unless you have your AH on.
3. You are not going to get enough heat out of the dash to keep an entire 41ft coach warm if the outside temps are cold.

Piper911 · 02-11-2025, 07:19 PM

Thank you all for your response. I will use the diesel setting on aqua hot and make sure I'm getting output from all registers. I've read about the kinking issue, but didn't think I was affected. I will check for that.

Thanks

36PFT · 02-11-2025, 07:49 PM

There is only a small exchange of heat from the engine to the Aquahot with the engine running at normal temp. I think it is around 10,000/12,000 BTU's, and the diesel burner is around 50,000+ BTU's. If you are driving in 30 degree weather, you will need the diesel burner to get heat out of the kozy heaters (registers). In 50+ degree weather you will get some heat from the kozy heaters with the diesel burner off. The fan in the Kozy heaters will not turn on unless they reach a specific internal temp. The engine preheat is only one works to heat the engine. Hope this helps. Stan

Foulwx · 02-19-2025, 06:54 AM

I'm not sure about what model Aqua Hot you have in your 2018. If it's a 400D, you do not have the engine loop and there is no heat transfer. If it's the 450D, you should.

The 450D does a good job without turning on the boiler on our 22IP.

Glenn

Terryt511 · 02-19-2025, 07:50 AM

Foulwx piqued my interest with his post. Thanks. It is super cold here in Cincinnati and we are bailing out this Saturday for Camp Margaritaville, FL. I wasn't sure of a couple of ways to run the AH while driving. At 15 degrees or so, the dash heat isn't going to keep my wife up to her desired temperature. We have a 450D AH and now I'm wondering how do you select the engine heat to provide its heat to the kozys. Is there a selection on the AH? I'll have to go out to our '25 Bus and see if that is one of the selections, in addition to electric and diesel. Also, does the genset need/have to be running for any AH to operate? Methinks the AH electric does require the genset, but not the diesel which, I think, is only 12 V.
Thanks for the clarification,
Terry

d23haynes57 · 02-19-2025, 08:05 AM

The "Cozies" are controlled by the thermostat system. On mine, they work regardless of the Oasis being turned on or not. When the thermostat calls, if the "boiler" is warm enough the zone pump(s) will turn on and then the Cozy fans will run. As long as the engine is supplying enough heat to the Aquahot you will have some heat. If you do need more just turn on the Aquahot burner. If you have the engine preheat option, when stopped for the night turn that on. Mine keeps the engine around 130F. Morning start is with a warm engine.