Buderus GB142-24: Repair or Replace?

RobertC

MA homeowner here seeking advice.

During a recent annual maintenance visit, my plumber (not the original installer) discovered that our sixteen year old GB142-24 seems to be leaking. There were a few drops of water in the corner of the underside of the top cover, and it appears that the air separator at the top of the unit is weeping - there are a few drops of water up there, and there was some white residue on the side of the boiler and a little pile of it in the bottom of the unit. There was no maintenance to do, as it seems "it's been steam cleaning itself."
In all these years, the only other problem was a wear item (igniter/flame sensor). And replacing the original, poorly designed trap, which disintegrated.

Some details: The system was installed by a large Boston firm that appears to have exited the hydronics business, and seems to have been a good install, although it was done shortly before the AM-10 control was offered, so it is managed via a Tekmar unit (360?) and a mixing valve, which I gather is not how it would be done today. The system has an outdoor sensor and an indoor thermostat and thinks it is connected to low-mass radiant (most of the radiation is massive CI radiators from the original gravity system) and runs at relatively low temperatures - on the coldest days of the year, the Tekmar may call for a circulating temp of 145F. Most of the time, the temps are much lower. DHW is via a SuperStor Ultra. Overall, it's been a comfortable and efficient system.

It's been suggested I replace the unit with comparably sized Bosch Greenstar, Lochinvar Knight, or possibly a Viessman Vitodens. Of those, my plumber, whom I trust, recommends the Bosch, with which he has never had a problem. From the little research I've done, I would lean towards the latter two for the stainless-steel HX and 10:1 turndown ratios - even the small GB is oversized most of the year, so the ability to go even lower would seem to be an advantage.

My question is: repair or replace? My inclination would be to replace, but - and I know we don't discuss pricing on this board - for a variety of reasons, money is tight, and surely even if it takes an entire day to replace the HX, that would be a fraction the cost of installing a new boiler.

Or would this be a classic case of throwing good money after bad (and perhaps risking that something else will break during the repair or shortly afterward (and that parts will be unavailable?) It seems Buderus pulled the plug on this boiler in 2018 - how long are parts typically or required to be available?

What do the wise and knowledgeable professionals of this forum advise?

Thank you!

Ironman

If the HX is actually leaking, then I’d replace the boiler. You may find that it’s hard to even locate one.

I’d recommend that you go with a fire tube boiler like the Lochinvar. The Green Star has an aluminum HX and is somewhat flimsy overall.

RobertC

Thank you.

kcopp

the boiler air vent is fixable... Inless you are adding a lot of water to the system at least see if you can wait until spring.
Can we get a few pix of the leak and staining?

Big Ed_4

The GB is older than 15 years old I assume before the AM10 . I replaced a few heat exchangers . Good boiler the GB , The Bosch I would recommend as a replacement, good German made like the GB.. Easy to work on once you have worked on a few..

If the cash is tight , you can't go wrong with a new heat exchanger , and start from scratch . The parts are still available , except the AM10

. How is the rest of the system ? What hot water tank do you have ?

RobertC

Thank you for these responses! There was some sludge in the trap, but the rest of the system rest of the system is fine. Here are some photos.

Mad Dog_2

Or... you could just upgrade to the King of All Mod Cons, The Viessman. They generally don't have these problems. Mad Dog

kcopp

Looks ok from those pixs. I would replace that vent top and that should by you time. if it has an issue coming off a surgical use of an oscillating tool would do the trick.

psb75

The GB 142 is a good boiler. Yours is burning quite clean. It will do very well with this high mass low supply temp operation. Obviously it has for quite some time. It will be challenging to find a new heat exchanger. Your question about various brands: there is an obvious price difference between the German aluminum mod-cons (Bosch/Bud.) and the next 'step-up" is to stainless steel (Viess./Loch). See if you can't get a few more years out of the GB if budget is tight.

RobertC

Thank you to all who responded!