New gas heat install.

chap007

I am converting from oil to natural gas heat and deciding if I should go with a hydronic Burnham boiler and hot water heater versus a combi boiler such as a Navien or Lochinvar. I have researched the above and people I know in the HVAC field like the combi units however the Plumbers that gave me estimates all seemed to favor the boilers. Any input would be greatly appreciated.

EzzyT

stay away from a combi.

Go with a boiler and either water heater or indirect tank.

EdTheHeaterMan

How long has your Oil Boiler lasted? If it is cast iron, it may have been there for over 30 years. Your Navien or Lochinvar Modulating-Condensing boiler has a life expectancy of 15 years. If you want something to last for many years I would recommend a boiler with an indirect tank. If you are selling the home within the next 10 years then I would go with the Mod-Con, and re-coop the savings. Then the replacement boiler is someone else's problem.

The Mod-Con will certainly offer you the lowest fuel cost for heat and HW.

This sounds a little morbid but I ask my customers over 60 years of age: " what condition will you be in at age 75 when you need to make a decision on a replacement boiler because the one you purchased today is at the end of its life? Will you have the $$$? Will your mind be as sharp? Do your older self a favor and get the one that will outlast you in this home.

chap007

I had a burnham oil burner for 20 years, really nothing wrong except for replacing the expansion tank. The oil tank was old and I decided to go with the gas. The boilers have the advantage with longevity but the combis seem more efficient and seems there is more labor in the installation since they have to install new flue pipes and a drain for the condensate.

Jamie Hall

Combis can work well — in some situations. You have to evaluate very carefully your hot water usage vs. you heating usage, however, as it is more common for them to be undersized for your hot water demands and oversized for the heating demand — often by quite a substantial margin. In which case you will NOT be a happy camper. Assuming you have to change your boiler and fuel, I'd go with a mod-con and indirect. If you don't HAVE to change, I wouldn't. You won't save much if anything on fuel.

ethicalpaul

Avoid a lot of extra piping, an aquastat, a circulator, extra labor, extra maintenance, undesirable linking of your hot water system to your heating system, and having to keep your boiler on all year by just getting a water heater for your hot water.

EdTheHeaterMan

If your boiler is only 20 years old, you have lots of life left in there. Have your thought about a Gas Gun conversion burner for you oil boiler? That is usually a lot less $$$ that a complete new boiler. and the efficiencies are sometimes better than the package Cast Iron boilers you might be considering. Looks like an oil burner, works like an oil burner, Just uses GAS! https://carlincombustion.com/ezgas-pro-burner-3/

Midco also has a lower cost model

Riello and Wayne also have Gas burners that fit oil boilers. Check with your contractor to see if there is a burner that will match your boiler!

chap007

Thank you all for your valuable advice.