I would like to replace my 1957 giant beast of an oil boiler (see pics here) There's nothing wrong with it per say, it's just big, old, over sized, and probably inefficient. I'm planning to move away for a few years and rent my home, and I don't want this thing to break while I'm gone and have to pay an HVAC contractor for an emergency replacement. I see 2-5 year old oil boilers on Craigslist all the time from people converting to natural gas, so was thinking I could pick one up cheap and install it myself. I managed okay with the hot water heater install and have a buddy who's a pipe fitter and can lend a hand if I get in a jam.
I had actually spent months planning a wood boiler install with thermal storage tank and a constant circulation ODR-based system. (This was put on hold due to above-mentioned short term rental plans) I did a fairly extensive heat calc using an online calculator and came up with 90K btu/hr at 0 degrees. I then got some input from some other knowledgeable folks combined with past fuel usage and am thinking it's probably closer to 75K btu/hr @ 0.
I also used the Taco circulator selection guide to assess the distribution side. I measured the baseboard length, pipe length and fittings for each of the two zones in my house. I calculated the equivalent length, flow rate and head loss for the two heating zones and one appears to be twice as big as the other (32.5K btu/hr 3.25 gpm @ 3.4' vs 56.5K btu/hr 5.65 gpm @ 20.8'). I was going to split the big loop into two smaller loops so there would be three roughly equal size, all <4 gpm @ <4' and then use a small variable speed circulator like the Grundfos Alpha or Taco Bumble Bee. Zones 1/2 are what I've got now, and 1a/1b are the proposed new zones after splitting Z1.
Based on the amount of baseboard vs the peak heating demand, I figured out I could get away with running lower water temps. The plan was to use several water storage tanks connected in series, batch burn the wood boiler and then have a constant circulation distribution system using a 4 way mixing valve with ODR, drawing hot water from the storage tanks and mixing with cold water returned from the zones.
One day, when I'm confident I'll be living here for a few years, I'll get back to the wood boiler. In the meantime, I'd like to put in a new(er) oil boiler so I'm confident the rental situation will go well.
So here are my questions:
1) What size boiler do I need?
2) Should I still split the one huge zone into two smaller ones?
3) Is there an oil boiler than can provide/accept lower water temps, or is that just a feature of gas mod con units? Should I get a small buffer tank and setup the same batch burn/constant circulation system, or is it not worth it with oil?
I had actually spent months planning a wood boiler install with thermal storage tank and a constant circulation ODR-based system. (This was put on hold due to above-mentioned short term rental plans) I did a fairly extensive heat calc using an online calculator and came up with 90K btu/hr at 0 degrees. I then got some input from some other knowledgeable folks combined with past fuel usage and am thinking it's probably closer to 75K btu/hr @ 0.
I also used the Taco circulator selection guide to assess the distribution side. I measured the baseboard length, pipe length and fittings for each of the two zones in my house. I calculated the equivalent length, flow rate and head loss for the two heating zones and one appears to be twice as big as the other (32.5K btu/hr 3.25 gpm @ 3.4' vs 56.5K btu/hr 5.65 gpm @ 20.8'). I was going to split the big loop into two smaller loops so there would be three roughly equal size, all <4 gpm @ <4' and then use a small variable speed circulator like the Grundfos Alpha or Taco Bumble Bee. Zones 1/2 are what I've got now, and 1a/1b are the proposed new zones after splitting Z1.
Based on the amount of baseboard vs the peak heating demand, I figured out I could get away with running lower water temps. The plan was to use several water storage tanks connected in series, batch burn the wood boiler and then have a constant circulation distribution system using a 4 way mixing valve with ODR, drawing hot water from the storage tanks and mixing with cold water returned from the zones.
One day, when I'm confident I'll be living here for a few years, I'll get back to the wood boiler. In the meantime, I'd like to put in a new(er) oil boiler so I'm confident the rental situation will go well.
So here are my questions:
1) What size boiler do I need?
2) Should I still split the one huge zone into two smaller ones?
3) Is there an oil boiler than can provide/accept lower water temps, or is that just a feature of gas mod con units? Should I get a small buffer tank and setup the same batch burn/constant circulation system, or is it not worth it with oil?