No problems in 20 years except the gas valve packed it in about 4 years ago and needed replacement. I installed the entire system myself and I'm not an HVAC tech either. This unit heats the PEX in-floor radiant tubing on 3 zones but the control panel which I got pre-assembled has 2 spare zones unused. I modified the panel to bypass the timer that controls automatic boiler firing for "maintenance". I see a lot of complaining about the boilers in this list of reviews but most of them have little to do with the actual boiler. Don't bitch about the pump, the zone control setup, the piping and all the other stuff hanging off the boiler and dictating what that boiler is supposed to do and when. You have to do off-season maintenance on any hydronic system too; you can't just shut it down in the spring and expect it to work perfectly when you want it going 6 month later if it sits idle the entire time in between. I run my boiler a minimum of once every 3 weeks throughout the summer and all it takes is 20 or 30 minutes to keep things humming when you want them to. The flow control valves often wants maintenance yearly but I've never had mine apart in 20 years without problems. You should be using softened water in it if possible and throw in a good quality glycol and pump lube additive with leakage protection. These are complicated systems that half the HVAC guys can't comprehend so they often modify them back to something they know or think they know–and that starts the problem ball rolling downhill. A boiler doesn't work like a forced air furnace either–you will be disappointed if it's a requirement that hot air be blowing up your skirt right now whenever you want it that way.

My heating bill has been $1000 lower a winter with this unit, I'd guess. I heat the garage as well. The house is on slab heated floors. I've had the furnace serviced twice in 14 years and have had only one issue, with the return drain line. The plumber/furnace guy said I didn't need all the stuff the installer used, as it was for a bigger building, not a house. I only vacuum and wire brush out the furnace each year myself before igniting it. I don't turn the thermostat past 18, as it gets too warm at night. Is a heat pump better? Not if it's minus 15 outside. LOL

Boiler installed 11-21-2001. Heats only 3 rooms. The heat is very inconsistent. Several parts have been replaced (zone valve control, power vent, pilot assembly with new sensor wires, direct vent fan) and as of this date 8-02-2014 it is still not running. Parts have been removed , which were difficult to get and expensive. My plumber, trained in Canada on your product, your trouble shooter and a variety of on line/phone techs can't determine the problem. No heat at all through 2013 winter in NJ which was very severe. Very little satisfaction when contacting the Rhode Island Office. Any name given to me was not the person who knew what to do. Limited heat in winters of 2012, 2011, 2010. Soon we will be in the winter of 2014 and I still do not have a functioning boiler. What is the Veissmann Corporation going to do for me??

Joerg Klempnauer – Vauxhall, Alberta: You purchased and installed a boiler without any thought as to serviceability? That's not the boiler company's fault. There are probably no Ferrari dealerships close to your town, either – does that mean Ferrari is a bad company?

Paid huge money for this system I have had nothing but problem after problem. The boiler has basically been rebuilt. The hot water heater has been replaced. They told me I must have hit it to break it? Never get straight answer. Spent twenty minutes on phone with viessman just trying to get someone to answer what the warranty is but no one wanted to answer the question. Do not spend the money.