Recent content by Mike Bernardo

Thanks Dana. There is a *lot* of glass in this place and no attic. Blower door was 50Pa/1780 cfm. Design temps are 2deg outdoor, 68deg indoor. Two of the biggest open-space rooms are 22K by themselves. Not sure if credible or not. <shrug> Yeah I'm not going to be able to do that kind of...

Yeah they tested pressure and combustion. The leak was definitely noticeable. Lots of bubbles forming. I did follow your advice for adjusting the min/max firing range and ran better with that for close to a year (seemingly) without issue. (Thanks!) However, using @Dana's sizing math, I always...

The leak was found after I made a service call for an extreme groaning/howling noise when the boiler went into high-fire. The techs performed a bubble test on the exchanger housing itself. (Top portion where it's joined by screws) After spending some time with Navien tech support, they all...

About 2 years later. This should come as no surprise to anyone, but this Navien has finally died. (Leaking heat exchanger) Navien is replacing the entire unit under warranty, but I am not super excited about this idea with a ~$6K labor bill alone, and back to square one with an oversized combi...

@Dana: Maybe we're looking at different rebates? I found this one: https://www.masssave.com/en/saving/residential-rebates/electric-heating-and-cooling/ It's very explicit on who is eligible to receive the rebate. "Must be a Massachusetts residential electric customer of Cape Light Compact...

@Dana : Thanks for the heat pump tips and explanation. The modulation behavior makes sense now and I can see why it's important to size these correctly for the room. Good tips on the rebates. Unfortunately they're only valid for customers of the bigger utility companies. Our little municipal...

Thanks again for the info! Looks like I've got more homework to do on this newer ductless tech. You mentioned earlier that multi-zone heads don't modulate with load. Is that a characteristic of any multi-zone solution in general, or specific product line? I had thought that my current indoor...

By my math, all zones running at 120F water = 14,834 + 4,560 + 8,312 + 4,000 = 31,706 BTUH. Isn't this well over the 17000 min fire rate of the 240? Even 1st+basement = 18,834. What am I getting wrong? Thanks for that fuel use comparison. Seems likely that my current mini-splits will be cheaper...

Great info! The Versa seems like it's worth investigating. I'm baffled at why HVAC contractors even suggest installing low-mass combi boilers for whole-house heating?? It seems that any combi boiler sized big enough for domestic hot water is guaranteed to short-cycle a zone somewhere? Doubly...

Our 4 year-old Navien NCB-240 (propane) has been problematic for most of its life. Many parts have been replaced and is currently acting up again. I was at my wits end and about to replace it with a different manufacturer, but as I learn more about mod/cons I'm starting to think maybe our...