Re-using old Viessmann boiler for potable hot water

jock22

Hi hoping to get some advice, I recently had a used Viessmann vitodens 100 installed in my house to supply hot water. The boiler is probably over 10 years old and was probably used with rads or in floor.

Is there any concern with installing previously used components that might have had glycol enriched water running in them? (Viessmann boiler, Grundfos pump)?

The Viessmann hasn't been used in 3 years not sure if that would give enough time to allow any residue to evaporate?

Ty

Jamie Hall

The residue -- particularly if there is any chance that glycol was used -- will not evaporate. Not inside a boiler. Nor, for that matter, will any boiler treatment chemicals which might have been used.

Both glycol and boiler treatment chemicals are toxic to varying degrees.

You will need to flush that boiler -- with very high flow -- and any other components very very thoroughly. A few hundred gallons might do it; a thousand or so might be better. And then take a water sample from the boiler to an accredited lab. to anaylse for any glycol or possible treatment chemicals.

I wouldn't touch it with a barge pole.

A much better idea would be to also get a nice indirect hot water tank and use the Vitodens to heat that...

ratio

Jamie Hall said:

I wouldn't touch it with a barge pole.

QFT

jock22

Thanks Jamie, greatly appreciate your advice. As it turns out ( I think I was scammed) the boiler is pretty much on its way out, the temperature sensor is totally blackened and the unit is fatigued over all. Lesson learned thanks to this board. Getting a brand new Navien tankless for now.