Home backup generator for Viessmann Vitodens boiler

Kindrex735

Hi, I’m trying to figure out what the best option is to be able to heat my house and power the well pump, fridge, and a few lights during power outages. The boiler is a Viessmann Vitodens 100-w and runs on propane. I know very little about how generators work but from what I’ve been reading it seems like a normal portable generator won’t produce a pure sine wave and that could do some kind of damage to the boiler, or the boiler might not run at all? My house has a cable for a generator that’s tied to the electrical panel, and the boiler itself is just plugged into a wall outlet. I’ve seen some posts that mention inverter generators, or regular generators with some extra device that can convert the electrical output to a pure sine wave, but I really have no idea what I’m looking for. Does anyone have any advice for what my setup should be?

hot_rod

There have been a lot of discussions here on generators, maybe do a search. Steve sells them, Moe back in NY specializes in generators and does hydronics.

Jamie Hall

To add to the valuable stuff above -- do look at it -- a sort of useful rule of thumb is that, like so many things, you get what you pay for. There are a number of manufacturers of very good, small, inverter generators which produce quite a passable sine wave, and should run almost anything. There are also a number of manufacturers (sometimes the same ones...) who produce cheaper generators which don't. The specs for the generator will usually have some information on that. In addition, non-inverter generators -- particularly older or larger ones -- are often very close to a pure sine wave. Then there is the question of capacity. You need at least enough running -- not surge -- capacity to run all the devices you want to run at once, plus at least half again the power draw of the largest motor-driven unit.

MaxMercy

If you stay with a generator that has less than 5% THD, you should be OK. Most portable generators use brushed alternators which produce a "dirty" sine wave which get worse under heavy load. The low distortion generators use brushless alternators which are much better, such as the installed Generacs.

Then there are "pure sine wave" portable types that use an inverter circuit to produce a pretty clean sine wave, but these are generally lower wattage units.