Thinking of pellet furnace for forced hot water and dhw off boiler

Hey Jason, welcome to Hearth. Let me help by clearing up that what you have is called a boiler. A furnace is generally a hot-air setup with ductwork. Now that that is out of the way, I installed a pellet boiler for my uncle it's a Harmon PB105. I was impressed with the unit, but bewhare that is is really a pellet stove with a nice water jacket. Same burnpot and all. The boiler tubes have rods you use to clean them and ash has to be removed manually. If you don't mind a little tending it's a nice unit. Some people expect a totally self cleaning unit, and those are made as well, just plan on 10K+ price. My uncle got his on CL for 6K, new.

Do you have an indirect water heater (seperate tank) or a tankless coil?

TS

Get in touch with Marc Caluwe in Bellerica MA. He has a couple nice pellet boiler lines and can steer you in the right direction. His number is 781-308-8583. I would advice purchasing a unit that is designed as a real boiler rather than something that has been adapted from an existing unit in a manufacturers product line. I'm sure he can put you in touch with someone to help you with your project.

1000 gallons of heating oil @ $3.75/gallon is $3,750.
with wood pellets you should be able to cut this in half with any decent pellet boiler.
This brings you to $3,750 / 2 = $1,875

If you pay $6 per bag of 40 Lbs, this corresponds with $1,875 / $6 = 312 bags of 40 lbs
Or 312 bags is around 6.25 Tons of wood pellets.

This seems a lot to me for a 2,400 SF home and for a mild winter like 2011/2012

How many bags are you burning per day right now?
How well is your house insulated?
Can you measure the smoke temperature (stack)?

I'm at about 2 bags a day, sometimes more. I seem to be getting a lot of buildup in the boiler. I'm cleaning and removing ash in the burn pot daily but the manual also states some of the other cleaning needs to be done just twice a season. However, with the way it builds up I'm diligent about staying on top of it and doing it every week. The house is insulated just fine. I have an attic cover and have newer windows and don't feel any drafts in the house. When I was heating with the oil it seemed to do a fine job. I'm not familiar with the smoke temperature (stack). How would I measure this? Thanks!

I think you are right within what you should burn, based on your oil consumption of last year (see above)
Nov to March is 5 months, times 30 days per month = 150 days x 2 bags/day = 300 bags

I would try to figure out how you can get an idea of your stack temp.
The high end boilers that are available in North America, like the Windhager BioWIN, have a stack temp of around 230F

I'm not sure what the Harman HydroFlex60 is supposed to be.
I remember reading somewhere on this forum between 350F-400F
If the stack temperature goes up, it's time to clean the top heat exchanger.