Wow, yesterday was a busy one…
We started a little after 7:30 and didn’t knock off until almost five. The problem with building an underground house is that you have to plan things like utility venting long in advance – and we sort of didn’t. Things got complex – but we almost finished. We didn’t run out of want-to, we just ran out of time and energy.
The job is still a few hours away from completion but we got far enough to know that the gadget works – or at least tries to; it doesn’t have any gas pressure yet.
Guess you are working on Ian’s cave? Yeah, venting for a gas fired on demand heater is important, as is a CO detector to go with it, though it should not be as big an issue as with a normal gas fired home heater.
What’s the life expectancy of the water heater?
The instructions for my gas-fired tankless call for “the vinegar treatment” annually; I’ve learned that my water is so soft – it’s rain water “stored” in a very large lake that goes through the usual Local Government Large Water System, Inc. treatment on its way to me – that using 50% for 30 minutes every third year to ensure heat exchanger cleanliness is more than adequate, as opposed to the recommended 100% vinegar for an hour every year.
Given what you’ve said about the mineral content of your water, does Ian have any special plans for protecting the heat exchanger on his?
Excellent question! And it’s one the whole venture would have foundered on, except I have neighbors who already tackled and overcame it. Ian’s plan is basically to depend on my self-interest to keep it running, and I have already studied
my Agrippamy neighbors’ methods of running vinegar through the machine on a monthly basis. Given how much less this heater will be used I don’t know if the frequency of cleaning will need to be increased or decreased, but believe me when I say I’m on it.WOW. Vinegaring monthly…..even in Florida with all the #@&% in that water we still got away with using 50% annually. But at least that was (mostly) “water” and not “caustic liquid abrasive compound”.
I have questions about the ‘monthly’ thing. My neighbors are kind of OCD. The water’s going through a softener before it gets to the heater so how much of a problem the dissolved solids really are is an open question. Best to assume the worst and see how that goes. You can always slack off later.
“You can always slack off later.” Sometimes, with mechanical equipment, “slacking off” is akin to hanging someone only once instead of twice.
A question I’ve asked repeatedly, and received varied and incomplete answers to, is “what damage, if any, is being done to the heat exchanger by vinegar flushing, especially in different concentrations.”
I get the impression no one outside the design team may actually know, and I’m not convinced they do, either, based on the responses to my questions. I have had only gas-fired Rinnai tankless units, which use copper alloy heat exchangers, and initially followed the owner’s manual recommendations of annually using a 100% concentration of standard household white vinegar for 60 minutes (which is 5% acidity, but concentrations of between 4% and 30% are available, so read the label; the “grocery store stuff” will – usually – be the 4-5%, on rare occasion 6 or maybe 7%, the 10-30% acidity is available for commercial, industrial or laboratory purposes but does show up in some outlets (you may find the 20-25% sold as weed killer), so caveat emptor applies – anything over 8-10% requires rubber gloves, rubber aprons and goggles). After the first such session I noticed the vinegar was a pleasant shade of light green, indicating lots of copper molecules in it, so I started backing off in both concentration and frequency.
I haven’t noticed any reduction in water heater efficiency by reducing the vinegar concentration and the frequency of application, but I don’t have a good way to measure possible efficiency reduction over time. I also don’t have any way, outside of an expensive “water heater autopsy” to determine potential heat exchanger damage.
I’m sure flushing with 100% vinegar annually for 60 minutes will keep the heat exchanger clean inside, but I suspect it will also sell a lot of new tankless water heaters, too.