Complicated Boiler Upgrade

energysaver

I do energy audits and upgrades in NJ and help homeowners get up to $10,000 in incentives to help pay for the upgrades. We perform the audit, manual J calcs, and the in-house upgrades we do are mainly spray foam insulation and airsealing; HVAC and plumbing are subbed-out.

I have a customer who wants a boiler upgrade/modification. Currently there is a 44,000 BTU 83% SSE hydronic boiler serving the upstairs and a 150,000BTU 80%SSE steam boiler for downstairs. Both units are located in the basement. The smaller hydronic unit is 10 years old and the steam boiler is only 3.

At this point the best my plumber came up with was to replace the smaller unit with a 70,000BTU 85% efficient unit; the reason for the upsize is that is the smallest unit available in that efficiency (85% is the min. requirement to get funding). He also said that the 90%+ AFUE boilers do not work well with hydronic baseboard. Is that right? Manufacturers websites I have read say they work.

Another alternative I am considering is to swap out the steam system in exchange for hydronic baseboard which I understand to be an invasive and expensive endeavor. But this modification means that one boiler (maybe <100,000BTU) with two zones can do the whole house. How big of a task is it and is it worth it?

I don't feel comfortable replacing a 44,000 83% unit with a 70,000BTU 85% unit. It seems like an insignificant improvement. Can anyone give another recommendation?

Thanks.

beenthere

Mod/con boilers work fine on baseboard systems.

Doubtful your area is going to be at temps that tehj baseboard needs 180° more then 15 to 20% of the time.

If the piping is done right. And teh installer sets up the circ for the proper amount of GPM.
The boiler will be able to be at condensing temp for 40 to 50% of the heating season.

Even when not operating at condensing temps, they are still more efficienct then conventional boilers.

Converting from steam to hot water. Weather you use the rads over, or install new baseboard is a bit intense. How much. Varies with teh piping that is there.