Aqua Hot losing boiler fluid

[brobox]

Originally Posted by Spdracr39

I had to replace my tank pressure cap. It leaked about a pint a month but because of the heat the top of the unit was never wet just stained. A new cap took care of it.

Entegras are non pressurized. Same plastic caps as windshield washer fluid reservoirs.

[voltdoc]

I had a 400LP on my 2013 and had a similar concern. Turned out to be the nature of the beast.

Besides the usual culprits, I checked all the connections at the heat exchangers (most can be done from inside the coach), the flexible piping that goes in/out with the kitchen slide, etc. I even pulled the burner to make sure the tank wasn't leaking into the Burner. Nothing found. Chalked it up to expansion/contraction plus evaporation.

When you say the level drops by 2" are you checking it at the same point in the burn cycle? Normally, the accepted process is to check the level as soon as the burner turns off after a burner cycle. This will be when the tank is at its hottest and the expansion tank the most full. At this point you can add fluid to the hot line on the expansion tank.

If you check at varying points in the heating cycle, that could easily explain the 2" differential.

As for the evaporation, within reason that is normal, but keep in mind the water evaporates more quickly than the glycol. Because of that, I have found over time that the antifreeze to water ratio increases above 50/50. If that's the case IMO topping off with distilled water is acceptable. The glycol is sticky and can cause problems like sticking valves, plus it is not as good of a heat transfer agent as water. To check the ratio an inexpensive refractometer is handy to have. The one linked also has a scale to check your DEF.

[alanrd749]

I have checked the fluid level at several different points in the heating cycle from a cold system to just after the heating cycle with the same results. The level seems to drop about 2” or so. Yesterday, with the system cold, the level was about 1” below the cold line. I added enough fluid to bring the level up above the cold line. Today, the level is just below the hot line with the system pretty much running all the time so guess everything is working okay for now.

I’m going to get a refractomer as voltaic suggested.

Thanks for all the help.

[JDANDDD]

Originally Posted by alanrd749

I have checked the fluid level at several different points in the heating cycle from a cold system to just after the heating cycle with the same results. The level seems to drop about 2” or so. Yesterday, with the system cold, the level was about 1” below the cold line. I added enough fluid to bring the level up above the cold line. Today, the level is just below the hot line with the system pretty much running all the time so guess everything is working okay for now.

I’m going to get a refractomer as voltaic suggested.

Thanks for all the help.

It’s probably air in the line somewhere, if it takes fluid every day or week for more than say one quart total then I would be looking hard for a leak. It holds around 12 gallons of boiler fluid. Do what Chuck said follow all the aquahot lines to the end with a good light and look for the leak with the system running.
John D

[Bob in Bend]

Make sure your cap is on tight and not cross threaded.

[Jburklo]

“even pulled the burner to make sure the tank wasn't leaking into the Burner.“

Voltdoc per your statement above I am currently getting a lot of exhaust smoke (smells like the AH fluid) leaking around my flame sensor and igniter around my burner area. I don’t seem to be losing fluid but the exhaust is getting worse. Any idea if this would be the fluid leaking into the burner? If so how would that leak occur? I was going to pull the burner this Spring to check since the coach is now in storage but your statement above piqued my curiosity.

[Steve 716]

There are two primary fluid lines coming from the top rear corners of the tank. The connectors on my coach were non standard and one of them leaked when my AH was running. Fluid ran from the port to directly behind my AH. I visited several parts shops, connector in hand, and was told that it is not manufactured due to faulty design.

Here is my procedure used to replace the connector:

The two main hoses are located at the rear of and on each side of your AH about two inches in from the rear and two inches in from the side. I didn’t have a good enough sight line to take better pictures but you can see the constant tension clamp for the left rear hose. This is the constant tension clamp that I recommend using because it securely clamps a uniform amount around the entire hose.

The issue is that the connector for each hose is poorly designed, does not make a good seal, and eventually the tabs inside of the connector will bend and/or break. For my left side connector, when I added boiler antifreeze to my overflow bottle it immediately ran back out at the connector. Some pooled on the top of the AH and some dripped down the side and rear.

The first time it leaked I was parked at a campground. I spent the better part of two days carrying the connector with me and looking for another one. Every company I spoke with said they don’t carry it because it leaks. I bent the tabs enough to make a seal that lasted about a month, then I devised an alternative. I replaced both sides and haven’t had any issues since. After replacing the connectors you will need to add antifreeze to your overflow bottle several times to replace the antifreeze that was lost. As a part of this process you will need to bleed the air out of the lines and add more antifreeze to your bottle to replace the air. You will see the air bubbles in the hose from your bottle to your AH. While you are at it you should replace this hose with a new and thicker clear hose, available from any auto supply store. (If your replacement hose isn’t clear you won’t see the air bubbles). When you no longer have any bubbles fill your tank to a level between cold and hot. The next few times you run your AH check the level until the tank no longer drains. Make sure you use the boiler antifreeze that matches the color of the fluid in your system. Do not mix the two colors that are available.

Repair instructions (this is the procedure I used):

(a) Use a pex cutter to make a straight cut about an inch above the existing connector. After removing the hose inspect your cut. Make another cut if your first cut wasn’t straight.
(b) Remove the existing connector.
(c) Attach 4 to 5 inches of new hose to the barbed end of the new connector. Secure with a constant tension clamp. This is the clamp you can see in the photo.
(d) Install one barbed end of the splice into the other end of the hose and secure with a constant tension clamp.
(e) Screw this assembly onto the top of your AH. I didn’t use Teflon tape to avoid any getting into the system.
(f) Place a constant tension clamp onto your existing hose, push the hose onto the open end of your splice, and secure.


These are the parts you will need to replace both hoses.

two each 1/2” MNPT to 3/4” barbed brass connectors
six each 3/4” constant tension clamps
8 to 10 inches of 3/4” heater hose (cut in half)
two each 3/4” barbed brass splice connectors

Depending on your access you will need from one to two hours for the repair.

[rggarrott]

We have had three issues with leaks in our Aquahot. All involved the piping connections on the back side of the Aquahot being too loose or piping being forcibly installed with bends that put the seals in the connectors under stress.

Before you start crawling into the basement take a close look at the Aquahot drip pan drain where it comes through the basement floor. If that is clean and dry, the problem is elsewhere. Good luck.

[KMOD]

Originally Posted by jeff.herren

Have you run the AH much since service? Having the overflow drop 2 inches from midway point between the hot and cold could easily have been a bit of air in the line from the service.

Mine did that (dropped that same level) but only after I had to use it heavily (as in heat for the coach) during a cold snap a month or so after a service a couple of years ago. Meaning up until the cold snap when it was used for just showers and hot water it wasn't enough of a load to drive the air out of the bleeder valve.

I guess you'll have a better idea over the next few days if it continues to lose fluid.

I have a 450 DE and I am also losing fluid as well. I have used a gallon in less than a month. I have used a scope camera and traced all lines and hose clamps, can't find any leaks. I do not lose any fluid unless I am using the zone heat heavily. When using just for hot water I do not lose any fluid. I am wondering if the brand of boiler fluid is evaporating when using heavily.

[voltdoc]

The newer aquahot models do not have a "closed" fluid system, so evaporation is a normal event. In my experience tho it is the water that evaporates most easily from the 50/50 mix.

I check the propylene glycol concentration regularly with a refractometer and the PG ratio increases over time, indicating it is mostly the water evaporating.

As the PG concentration creeps up, I top off with plain distilled water to attempt to get it back to proper levels. Too high a concentration of PG will negativity impact heat transfer and cause check valve sticking.

However, my consumption is less than a liter every three months and we are full time. But we do stay in warm climates and heavy heating is not a normal thing for us.

[jeff.herren]

Originally Posted by KMOD

I have a 450 DE and I am also losing fluid as well. I have used a gallon in less than a month. I have used a scope camera and traced all lines and hose clamps, can't find any leaks. I do not lose any fluid unless I am using the zone heat heavily. When using just for hot water I do not lose any fluid. I am wondering if the brand of boiler fluid is evaporating when using heavily.

I had a bad main thermostat, and it caused a boil over out the overflow tube exiting under the coach. Lost a LOT of fluid quickly on that one.

I think a bad high limit can cause the same thing.

Did you notice a pool under the coach? May not have if you were/are on rock in the site.