A Tankless Job – Installing an Aquastar 125B LP Water Heater

Yes, that’s right…it was a tankless job. This week’s goal was to complete the domestic hot water heating system by installing the Aquastar 125B LPS tankless water heater. For those of you not familiar with tankless water heaters, a tankless water heater is just what the name implies—instead of heating a tank of water 24 hrs a day, the tankless water heater heats water only when there is a demand for hot water. This makes them much more energy efficient than hot water tanks.

This particular model is especially made for solar-assisted domestic hot water systems. It has a gas control that modulates the burner output in response to water flow. In other words, if the incoming water has already been preheated, it will modulate down the flame to keep the outlet temperature constant and reduce gas consumption.

Of course I thought this would be a breeze to install (since it was my second Aquastar installation), but low and behold Murphy’s Law came into play. The week started out well enough. My first goal was to get the gas line (black pipe) run from the exterior of the house to the Aquastar. That went without too many hitches and while I was at it, I roughed in the lines for the eventual clothes dryer and kitchen stove.

Once, the gas line piping was completed I called up the LP gas company and within two hours they arrived to fill the tank and check the lines. Speaking of LP gas companies, I must inform you of my new rule: I will call a contractor and/or service company twice. If I don’t get a worthy response, I cross them off my list. This scenario came into play while trying to find a reputable LP gas company.

I decided to first go with a local co-op for service. I’d rather spend my money on the local economy versus a large conglomerate, but after I placed the second phone call to this nameless local co-op without a timely response, I decided to look elsewhere. As it ended up I didn’t have to look very far. As coincidence would have it, I was working on a cordwood wall one day when a representative from Tru-Gas came knockin’ on the door. He remembered a phone call that I made a year ago asking basic questions about their service and he decided to take a chance and swing by the house to see if I had installed a tank yet. Needless to say, his timing was perfect. Not only that, but their service has been impeccable. All of my questions were answered in a professional manner and they were on-time with all of their visits. Kudos to Tru-Gas.

So the tank was set, filled and the lines tested. All I had to do was to hook up the water line from the solar tank to the tankless heater and reconnect the output to the hot water supply. This would be easy I thought.

Well, the water hookup wasn’t too bad. I really dislike the water hookup connections on the Aquastar, but I dealt with that issue. The manual says that metal pipe should at least be used a few feet on either side of the water connections to/from the Aquastar. I obliged and used galvanized pipe. Now for those of you who have read the journal for a while, I really don’t have much of a love affair with galvanized pipe, but I decided to use it anyway. I made all my connections, turned on the water supply and fired up the Aquastar. Everything appeared to work just fine.

I opened up the washtub faucet and a fairly healthy supply of hot water poured out. The power vent on the Aquastar turned on and exhausted the flame gases to the outside of the house. Wow! This was so cool…I mean hot! Everything was working just fine.

I then went to turn on the shower which has a low-flow shower head and got nothing more than a trickle! Not good. I had heard through the grapevine that some people weren’t too happy with their Aquastar heaters because of low flow problems. This occurs most often when there is a demand for hot water that outstrips the output from the Aquastar. I never quite understood what the issue was, because Jo and I have been using an Aquastar at our house in Illinois for years without any problems whatsoever.

I contemplated what the problem might be. There was nothing in the user’s manual to indicate that it could be a problem with the Aquastar unless the inlet water filter was plugged. Since this was a new unit, that didn’t seem likely.

I wondered if the 1/2″ pex supply and outlet lines might be too small. So, I decided to go to Menards and change to lines to 3/4″ pex. After returning from Menards I discovered that the galvanized pipe fittings were leaking in a few places. (Enter into the picture problem #2.)

Well…it was getting late into the evening, but I decided to forge ahead and change the water lines to 3/4″. I also wrenched on the galvanized pipes to hopefully stop the leaks. I turned the water on and immediately both the room and myself got a shower. Oops…I forgot to crimp a connector…no big deal it’s only water. (New Rule: Don’t do plumbing late into the evening after a long day.) After fixing my mistake, I turned the water back on and turned on multiple faucets. Same results. Dang! Plus, the galvanized pipes were still leaking.

That was enough fun for Wednesday.

Thursday morning, all bright-eyed and bushy tailed I drove over to Menards for more pex fittings. I figured the problem must be with the 1/2″ manifold that connects all hot water faucets to the main line. I figured there wasn’t enough flow to run more than two sources off the manifold at the same time. My solution was to bypass the manifold completely and connect the 1/2″ pex line from the shower directly to the 3/4″ supply line. Secondly, I decided to replace the galvanized pipe that was giving me problems with pex instead. (So much for following the manual.)

Okay. This was surely going to fix the problem. (Don’t call me Shirley) I turned the water supply on. No leaks! I then turned on multiple faucets and then the shower. It was better, but not much. Dang!

Okay. Back to the drawing board. I started thinking that either the Aquastar was my problem or I might be forced into using 3/4″ pex all the way to the shower head. I had looked on the Internet before to see if I could find any solutions for low flow problems with the Aquastar, but I didn’t find anything useful.

I then thought of other words to give Google and here’s what I submitted: “Aquastar 125 flow adjustment”. That did the trick! I found a bunch of articles on the Aquastar that were of use!

Now I presume that a plumber probably knows that there is an adjustment to the Aquastar to allow for greater flow, but because I don’t install these things every day, I was at a disadvantage to say the least. I am quite displeased that Aquastar doesn’t include this information in their manual. Considering that their basic models are now sold in most home improvement stores, you would think that it would be to their advantage to give home owners a few tips on how to correct this problem instead of the owner becoming frustrated because their product doesn’t produce enough flow.

I made multiple trips back and forth to La Crosse thinking that my problem was with my plumbing when all along it was a simple turn of a screw to fix the problem. (Okay, I feel much better now that I let off some “steam” and I had a chance to “vent.” Thanks for listening.)

On a much happier note, the domestic hot water and the solar heating systems are now complete and ready for this coming winter. I really haven’t had much of a need for the Aquastar this summer since the solar heat exchanger has most of the work for our hot water needs, but it won’t be long before cloudy, cooler weather takes hold. Sometime during the month of September, the tarps will be removed from the remainder of the solar collectors and I’ll start dumping Btu’s into the sand bed.

Next week, it’s back to more mundane things like cordwooding.