How to winterize an electric tankless?

[Tim]

I am installing a Bosch Powerstar AE125 tankless hot water heater in my cottage. I turn the power off during the winter when I am not there. I usually drain the plumbing system and add some RV antifreeze in toilets and sinks.

When I called Bosch, they did not feel that draining - even when using pressure - would get all the water out. When I suggested pumping in some RV antifreeze they said it wasn't recommended - although they didn't know why.

Does anyone have any ideas? Taking the unit out whenever I leave isn't a feasible plan. Other than draining the system and maybe using a hand pump to put some RV antifreeze in the tankless is my only idea. Comments?

[junkcollector]

One idea that comes to mind is maybe plumb in a fitting so that you can blow the water out with an air compressor? (Low pressure)

It's just a thought.

[Bumblerazz]

yup, I agree that blowing low pressure air through the system is your best bet. let it blow for quite some time as well, say +5min. other than that you're SOL as those thin copper coils will burst easily with the smallest amount of water in it, and patching/repairing it will be a bear to say the least.

[Tim]

Thanks guys. It seems that blowing low pressure air should get most of the water out.

However, just to be sure I was going to reverse my hand pump so that I draw RV antifreeze into the unit. Is there any reason that RV antifreeze would hurt anything?

[Bumblerazz]

it probably won't hurt the unit, but antifreeze is a poison and having it in your potable water source (showering, cooking, etc...) is not a recommended practice. I wouldn't do it. I know you can flush it out in the spring, but trace amounts may remain and though you may not get sick that day, long term effects are unknown. It's up to you.

[junkcollector]

it probably won't hurt the unit, but antifreeze is a poison and having it in your potable water source (showering, cooking, etc...) is not a recommended practice. I wouldn't do it.

I agree. I'd skip the antifreeze. As long as you blow the water out, and leave the plumbing system to vent, (such as leaving some faucets open) Your water heater should be fine.

I would plumb in a hose bibb below your heater. On the other pipe plumb in a valve, and into the valve screw in a air fitting. When you blow out the water from the heater, you could then attach a garden hose and run that to the drain. When the water is all blown out, you could leave the hose bibb open. You could also plumb in another shutoff, if the heater doesn't have one already, so that you can close it and keep from pressurizing your whole system with air.

[joed]

it probably won't hurt the unit, but antifreeze is a poison and having it in your potable water source (showering, cooking, etc...) is not a recommended practice. I wouldn't do it. I know you can flush it out in the spring, but trace amounts may remain and though you may not get sick that day, long term effects are unknown. It's up to you.

The RV stuff is specifically made for potable systems.

[Bumblerazz]

Joed is quite right. I just looked up the MSDS for one type of RV antifreeze and it talks about "central nervous system effects", as most liquids containing propylene glycol do, but you would have to ingest the stuff straight. having it diluted through many rinses and uses would not likely have an effect.

Again, I wouldn't do it, but its up to you.

[AllanJ]

I would go ahead and use antifreeze. And I would have to use extra antifreeze to be sure that every coil and nook and cranny received antifreeze leaving no pockets of plain water.

After you flush out the system a few times next summer, the amount of antifreeze you might get on you from taking a shower would be much less than what y ou might get on you when you change your car's antifreeze yourself.

[Fischer]

Additional safety valve would be to put a pet**** inline just below the heater. That way you could open it, and let it drain and keep it open over the winter.

[joed]

Definitely need a drain that can be left open all winter. Condensation will create water inside the heater that will freeze. Best to have a way for it to drain above freezing.

[Tim]

Thanks everyone for all the ideas.

I think I'll drain the system and then fill the unit and all its coils with RV antifreeze. Then I'll open a drain just below the unit and let the antifreeze drain out. I'll leave the drain open until I use the unit again.

[Fischer]

Thanks everyone for all the ideas.

I think I'll drain the system and then fill the unit and all its coils with RV antifreeze. Then I'll open a drain just below the unit and let the antifreeze drain out. I'll leave the drain open until I use the unit again.



Good Idea.