It seems unlikely that both boilers would independently encounter the same error condition at the same time. I would check something that is common to both that could cause the issue. Have the tech check for voltage or gas pressure issues before swapping out any components.

Braytonak, The GV was one of the first boilers to cross over the 84-85% AFUE which put it in the condensing range. Yes W/M put a circ in the boiler to combat that but they also added a temp mix/bypass valve in conjunction with it. So feel free to dial that outdoor reset lower. Depending on how your boiler is piped, primary/secondary (which is best) you could use the boiler circ to inject heat into secondary heating loop(s) and appreciate even lower water temps. Without primary/secondary you must be careful to not cycle the boiler to much when operating in the lower temps (small trade off). I'm hoping this boiler was installed after the plexvent problem or has been upgraded since to Cat II Stainless, right? My personal take on the plexvent issue, it was brought on by improper installation, sealing, lack of support, improper cutting, and using non-UV fitings outside. Aside from that it's tough to screw up gasketed stainless pipe with clamps.

Dear forumites, I live in a condo (one of 3 units in an old house) in the Northeast. We currently have steam heat using oil. We have one tank and one boiler, for the whole house, which is probably 10 years old and in decent shape. The units share the cost of the heat. We're considering changing to gas because of high oil prices, environmental concerns, and U.S. oil-dependency concerns. We can get a new high efficiency gas boiler from our gas company for $799 (or a less efficient for $499). We had an installation contractor come out and he said it would make more sense (cost wise) to stick with one boiler for all 3 units rather than install separate boilers for each unit. He gave a very rough estimate of around $5,000 for the conversion, including the cost of a $799 boiler (I should mention we have a gas line to the house and run our hot water heaters and our stoves on gas.) He also said, given the age of the boiler, that we could put in a conversion burner which would be cheaper but since he doesn't do those he didn't offer any more information. My question is this: should we just add a conversion burner or should we replace the boiler? I understand that using a conversion burner will result in a loss of efficiency but is it safe to do so? It seems to me that the boiler was made to work with oil. We're interested in not just spending less on fuel this winter but also in being environmentally responsible. Is an oil boiler with a gas conversion burner likely to emit more pollution? Thanks for any advice!

Sometimes you have to play with the cards you have. Given the limited boiler expertise in the area, there may be no other choice and complaining to Buderus can't help. The company won't want to put time and money into training a tech to service a very limited number of boilers in their area. They might just quit servicing boilers. A boiler has a lot in common with a furnace. Off the top of my head, things that can shut it down are a high temperature safety switch, flame roll-out switch and blocked vent switch. Bruce, do you have the install manual for your boiler? I found what looks like right one very quickly and there is a diagnosis flow chart in it. Here is a thought for you. If it is most cold when this happens, perhaps your gas pressure is dropping too low