Buderus

Glenn Sossin_2

While this boiler can handle a low return temp and not crack, I concur with Weezbo, it's something to try and prevent from happening unless the boiler is designed for it. Then the more you condense, the higher your system efficiencies are likely to be.

Your flue pipes will potentially rot away spilling dangerous combustion by-products into the home. Your chimney, if its masonry can be compromised.

One these pics is the rear jacket panel of a large boiler, with twin returns, that was condensing. You can see where the where the pipes were. This boiler cracked and was removed because it leaked - I believe it couldn't handle the shock of the low temp return.

Maynard

Buderus

I Seem To Remember Installing Buderus oil Boilers In The Mid To Late 80's That Needed A Bypass On The Boiler Return Line To Prevent Condensing? Do The New Buderus Boilers Spec The Same?
What Problems Can Too Low A Return Water Temp Cause To Combustion?

Weezbo

oil combustion has a part in just how long the boiler will stand

the test of time.

the types of emitters also have some relevance as does the way it is zoned, the supply water temps...and the return temps. the control strategy and water flow also is part of the mix.

certain Boilers have "options" as to the control that you have to chose from...depending on your piping arrangement there can be advantages and disadvantages in various strategies.

The Buderus Boilers now have a new control,...i haven't utilized one just yet, instead i am considering the Slant-Fin Eutectic.

here is the spiel on 215's they can have return temps in the 108 F due to the thermo stream design....

i am a hold out with partial differential forever the safest bet. that's me.

if you run the stacks too cool or swamp the boilers , no matter who makes them,.. it is not a Good Thing, unless they are designed for condensing ...

Glenn Sossin_2

Low return temp

While this boiler can handle a low return temp and not crack, I concur with Weezbo, it's something to try and prevent from happening unless the boiler is designed for it. The the more you condense, the higher your system efficiencies are likely to be, but you should protect the boiler from condensing unless it's designed for it. Look at thermic valve to protect your boiler. attached spec

Your flue pipes will potentially rot away spilling dangerous combustion by-products into the home. Your chimney, if its masonry can be compromised.

One these pics is the rear jacket panel of a large boiler, with twin returns that was condensing. You can see where the where the return pipes were. This boiler cracked and was removed because it leaked - I believe it couldn't handle the shock of the low temp return.

The other two I got off web somewhere but they make the case to try and avoid this condition. It's potentially lethal

Bob Harper_2

Venting Buderus G-215

Buderus requires masonry chimneys to be relined. Not optional. If you are that close to condensing, why not use stainless chimney connector right to the appliance collar instead of 26ga. galv. pipe? That's what I'm doing on mine. I'll post pics when done. I'm installing it with a Logamatic control with outdoor reset and indirect tank. I'll track the numbers and post as the season goes on.

Good point though, when you have a condenser, it requires close monitoring, frequent inspection and testing, and a high quality low level CO monitor in the home.