Community Forums

Wayne R · 02-06-2009, 12:12 PM

I just finished servicing my Hydro Hot. I replaced the fuel filter and fuel nozzle. I cleaned the burner ,electrode and set the gap with the supplied tool. It still seems to be running rich. Today I decided to check and make sure I had not bumped the electrodes while installing the motor assembly. All looked good. So I decided to change the setting on the air intake. After experimenting for awhile I found it burned cleaner with the air choked off about ½ turn from where it was. The unit has a pink mark where the factory set it. Has anyone else adjusted the air intake for a cleaner burn? I am thinking I might want to get a fuel pressure gauge and make sure I am getting 145 PSI of fuel pressure.

Roger Berke · 02-10-2009, 04:17 PM

Wayne

The air intake setting was set by Aqua-Hot by using an exhaust gas analyzer when they built your Aqua-Hot (that is where the red mark came from). If you decrease the air supply, you will run the risk of overheating the unit, especially if you take your coach into a high altitude area. The air intake should not be set lower than the painted mark, or about ½ way.

If your Aqua-Hot is not running well, you probably have another problem. Possible that fuel pump is not dispensing fuel at the recommended 145# setting or the blower motor may be running too slowly. Sometimes the unit will appear to run a little rich until the combustion chamber comes up to operating temperature, and then the exhaust will clean up. This is normal.

When you cleaned the combustion chamber did you also clean the interior (the inside of the Webasto burner)?

You can purchase a fuel pressure tester gauge for about $120 or make your own by using an old nozzle. You check the blower motor with an RPM gauge.

- Roger Berke -
Moderator - http://autos.groups.yahoo.com/...p/HydronicRVHeating/

Wayne R · 02-10-2009, 06:02 PM

Roger, Thanks I have read the service manual and I am considering getting a fuel pressure gauge. I suspect a fuel pressure issue. I did clean the inside of the unit with the combustion chamber removed.
This unit was on the recall list and the combustion chamber had failed badly. According to the tech it was the worst he had seen. It also has always run rich compared to others I have serviced. It does not seem to be getting any hotter than normal and choking the intake down does produce a cleaner burn.
I have a couple of ceramic tiles I put below the exhausts pipe. They were getting really dirty from the exhaust before I choked it down they are now staying clean. Not that that is a good check. I did look at the air intake on 2 other newer units and the butterfly is closed considerably more than the marks on mine indicate.
I am only using it to heat hot water right now and it only runs for a few minutes at a time.
I have another complete motor assembly at my home base from an Aqua hot that developed a fresh water leak in the heat exchanger. I plan on swapping units before I purchase a fuel Gauge.

Wayne R · 02-10-2009, 09:02 PM

Roger,
I reviewed all the posts on the yahoo group, good info and help. I will look through the available files as soon as my membership is approved.

Any hints on making a fuel gauge from an old nozzle?

Roger Berke · 02-11-2009, 09:05 AM

Wayne

I think that I approved your membership in the Hydronic RV Heating group this morning. Check out the files area, where you will find troubleshooting guides that I wrote and directions on how to do annual service.

I purchased my fuel pump pressure tester from Aqua-Hot. To build your own you need a nozzle, which you drill and tap for a pressure gauge. I don’t have an old nozzle right now, but if you want one, I will save one and send it to you on the next service that I do.

If you have a spare burner, you are good to go. If you need assistance you can contact me directly.

- Roger Berke -
Currently in Mexico Beach, FL
Moderator - http://autos.groups.yahoo.com/...p/HydronicRVHeating/

Wayne R · 02-11-2009, 09:19 AM

Roger,

Thanks, I have a couple of used nozzles. I will make up a fuel pressure gauge and check mine. Does the pressure adjustment usually correct low pressure?

Alpiner’s with Hydro Hot the Yahoo Group for Hydronic RV Heaters has a lot of good info.

Roger Berke · 02-11-2009, 09:49 AM

Wayne

There is a adjustment screw on the side of the fuel pump. You can normally adjust the fuel pressure to the recommended #145 unless the fuel pump is so badly worn out that there is no adjustment left.

- Roger Berke -

Wayne R · 03-10-2009, 06:27 PM

while I finally got it running right. I repacked the bearings ( not necessary just wanted to check them). replaced the electrodes, fuel solenoid and another new nozzle. I also adjusted the fuel pressure from 140 to 145 and cleaned the burner and combustion chamber.
It now burns clean I cant even smell diesel when I am standing over the exhaust. This unit has 3250 hours on the diesel burner.

EngineerMike · 03-10-2009, 06:57 PM

Mine has a good solid 3 hours on the burner, and smelled diesely from the get go. Guess I need to do a full service on it.

Wayne R · 03-10-2009, 07:06 PM

Emike,
I don't ever remember mine running this clean. I can sleep with the bedroom window open and not smell it ( my exhaust exits below the bedroom slide out). I thought they all smelled bad, until friends with newer units parked next too me. Theirs burned really clean like mine does now.

EngineerMike · 03-10-2009, 08:16 PM

That's what I was thinking after reading your post, i.e. that neither of the 2 units I've had/have were set up to burn properly

dgerstel · 03-11-2009, 04:59 PM

Wayne,

Great information! I have always noticed the black spots on the ground, from the generators and Aqua Hots after rallies. Since I am just getting ready to do a maintenance on ours, the timing of the information is perfect for me.

Thanks,

Cookiejar · 03-12-2009, 06:52 AM

My Hydro-hot exhaust was smokey and oily. I took it to Lazydays, had service, new nozzle and filter. Now my exhaust has black soot. What do I need to do. Thanks,

Wayne R · 03-12-2009, 08:42 AM

CookieJar,

The first thing I would check is the nozzle, brand new nozzles can be bad. I had a bad one and spent a lot of time trying to fix a sooty problem that turned out to be the nozzle. I have read just touching the end of a new nozzle with your finger can ruin them. Also fuel pressure may be low it SB 145. Take a look at the Hydronic Heating forum http://autos.groups.yahoo.com/...p/HydronicRVHeating/ Roger Burke the administrator is very helpful. He also has a parts store at http://s271809615.e-shop.info/ he is offering free shipping for now. A new nozzle is $13.

WRV did us a favor and installed our units in a very serviceable location. I just sit in my camping chair (bad back) and work on mine. I have helped others that require you to be a contortionist.