Good system setup to replace oil boiler / hot water

[mtbikerj]

With the rising price of oil, I'm looking to get rid of my oil boiler and replace it with (probably) a pellet boiler and some form of backup.

I've read through many posts on this site and found many helpful insights, but still need some advice.

I have a small 1400 sq foot cape in Massachusetts currently heated by baseboard hot water off a Burnham v-73 oil boiler. Hot water is supplied by an indirect tank "Amtrol - BoilerMate." I go through 900 to 1000 gallons of oil per year, but am making improvements to insulation in the house this summer, so hopefully the btu requirement will go down from that next year. I have only one flue which is being used by the oil boiler. I also have to keep the mortgage company happy and want to have something that will run when I'm on vacation in the winter. From what I've read, for the bank to be happy it means I need a "primary system" of either oil, gas, or electric.

I am trying to find the best solution to save me money in the long run, but I am at a loss for what to do. Natural gas is not available on my street and I can't do solar because there are too many large trees around my house, on all sides including the south. My house sits on about 1/4 acre and I don't have the room (or the time) for wood. I also don't have much room in my basement for heat storage.

Since I was hoping to remove oil all together, partly because I don't trust oil boilers to work well if they aren't run frequently and partly because home heating oil is pushing $5 a gallon here in MA and it would be heating my hot water in the summer. I was thinking installing a pellet boiler and also an electric boiler to call my primary system (even though I would only use it for domestic hot water in the summer and when I'm on vacation in the winter). Is that a good option? If I did this, should I keep the "BoilerMate" for hot water and let the electric boiler fill it during the summer and the pellet in winter? Would this be efficient. Are there better options besides this setup?

I'm o.k. spending 10 to 15K(max), but I want a design that is as efficient and saves me money. Does anyone have similar situations where you can tell me what you have done?

Any advice would be great! Thanks.

 

[SmokeEater]

Mtbikerj, I just installed a PB 105 Harman pellet boiler to heat my 30 year old cape. I can't give you much good data because I just fired up in late Feb of this year, but I am heating 2 floors, the basement, and the DHW with pellets. I don't have the radiant on the main floor completed and a lot of the heat is going into the basement. In fact the temps down there look like they're averaging 74 F when the main floor thermostat is set a 71. The Harman can hold 5 bags of pellets in its hopper and even though I don't have the conduction plates all installed and have no reflective insulation yet, I'm using and average of 2.2 bags per day since first fire. I had a hot air furnace in the cape and it was fired by wood and oil. If oil only was used to heat the home, I'd go through about 200 gallons per month. Translates to about $300 for heat and hot water with the pellet boiler and $800 per month for just heat with the old hot air furnace on oil. I do now think that that old hot air furnace was very inefficient. Though the time between Feb and now has been unusually warm, I think that the pellet boiler will be saving a good amount of heating expenses over the old system. Be aware though that this boiler is not a fill and forget. It requires a 15 minute weekly scraping and cleaning and will require a good cleaning at the end of the season.

 

[maple1]

I would consider kicking the oil to the curb, and replacing with an electric boiler (mainly for backup heat), an electric water heater (insulate the crap out of it), and a pellet or wood stove. You should have enough money left over in your budget for a mini split heat pump too - the electric boiler & water heater should total no more than $2500 or so. That's without knowing a whole lot about your house layout, aside from that it's small.

 

[mtbikerj]

SmokeEater, thanks for the data. How are you heating you hot water? Will you fire the harman all summer or do you have something else there?

Maple1, thanks for the advice. I was thinking I should get rid of the oil altogether. By electric water heater, I assume you mean a tank heater and not an instant heater. I'm not real familiar with mini split heat pumps. I'll take a look into that. As far as a stove instead of a boiler, I'm not sure if I can do that. It would work for three rooms on the first floor, but one of them is pretty separated and the least insulated of all our rooms, so I would be afraid of that one getting too cold.

 

[SmokeEater]

SmokeEater, thanks for the data. How are you heating you hot water? Will you fire the harman all summer or do you have something else there?

I have a Smart 100 indirect water heater with a Watts mixing valve connected to the pellet and oil boiler. This summer, in the off heating season, I plan to periodically fire the pellet boiler and heat the tank to max temp(I've had it to 185 F) and that will provide DHW for the house. I think it should only need to be fired about every 3 or 4 days.

 

[maple1]

SmokeEater, thanks for the data. How are you heating you hot water? Will you fire the harman all summer or do you have something else there?

Maple1, thanks for the advice. I was thinking I should get rid of the oil altogether. By electric water heater, I assume you mean a tank heater and not an instant heater. I'm not real familiar with mini split heat pumps. I'll take a look into that. As far as a stove instead of a boiler, I'm not sure if I can do that. It would work for three rooms on the first floor, but one of them is pretty separated and the least insulated of all our rooms, so I would be afraid of that one getting too cold.

There are all kinds (too many) of things to consider, variables & options. I don't know about the economics of pellets in your area, & how much a pellet boiler would cost, but after my winter of trying to figure out my situation, the one conclusion I did come to was that the oil should go, if it is only going to be used for periodic backup and summer hot water. Electric boilers are cheap & take up no room - just getting rid of the oil tank & all the liabilites that come with it is a major factor. Keep in mind though that if the boiler gets to seeing a lot of action, your electric bill will get to be more than your oil bill was. Electric water heaters are also cheap and more economical than heating water with an oil burner if they are well insulated. I also have baseboard heat and would never replace a boiler with a stove - can't beat the comfort. It always comes down to personal preferences & situations. How much is a decent pellet boiler?

 

[DBoon]

Hi mtbikerj, I was going through the same exercise about four years ago, with the same basic situation as you - one flue, oil boiler already installed, cast iron radiators, 1250 square foot house, no natural gas option, etc.

I really wanted to get a combination oil/wood boiler. There is one available, but after researching it, I decided that this was not the way to go. So I bought a woodstove instead and I found that the mess inside isn't as bad as I thought it might be, and the heat distribution (with insulation upgrades to the house) is better than I thought it would be. I do miss the cast iron radiator heat though.

I'm still looking to replace my oil boiler (1970s vintage). Here in NY, the regulations will require ultra-low sulfur heating oil by July of this year. Next summer, I'll likely replace my existing boiler with a condensing oil boiler since I believe the reliability will be very good with the ultra-low sulfur heating oil (sure, they are supposed to be fine with the oil we have now, but....). The big benefit with the condensing oil boiler is that I can get a sealed-combustion side-vent or chimney vent. I could go with the chimney vent today, but make it side-vent in the future, and (from what I have read) the side-vent on a properly running condensing oil boiler will not be as sooty as a power-vented standard combustion boiler. That is a big plus as I don't want a black splotch of soot on the side of my house where it would vent (if I ever side vented it). That would free me up for another use for the flue. The downside is about $2-3k more cost for condensing boiler compared to standard oil boiler.

I considered the PB105 pellet boiler from Harman, but given that I am away from my house for >2 weeks at a time, this wasn't an option - too much cleaning required in weekly (or less) intervals. There also seemed to be a fair amount of reliability issues with the PB105 four or five years ago, and that turned me off as well. Plus, at the time, wood pellets and oil at $2.50/gal were about the same cost per BTU, so there was no real cost savings.

I also looked at a propane boiler. Downside here is that the propane tank is stored outside and I didn't have a good spot for it (small 1/4 acre lot, just like you). Plus, cost per BTU is same as oil.

So, my focus will continue to be to 1) reduce oil consumption (blower door test is happening today), 2) use woodstove as much as possible (I save about 150 to 200 gallons per year by burning wood when I can), 3) get existing heating system replaced with a more efficient oil boiler. I've gone from ~1000 gallons/year to ~550 gallons/year (not counting the 150-200 gallons saved by burning wood in the stove) with insulation and weatherization improvements. I think I can get down to 475 gallons/year with more attic insulation and air sealing improvements, and then get down to ~350 gallons per year with a new boiler (and subtract 150 to 200 gallons from that that I save by burning wood). Then, my oil cost would be down to <=200 gallons per year - not zero, but pretty low and tolerable, and if I could burn more wood (if I was around more), it would be even less.

This was my thought process, findings, and current plan. Perhaps you'll find something useful for yourself in my exercise and plans.

 

[willworkforwood]

900-1000 gallons of oil for your house size in MA is WAY too much. So, you have already identified known issues that you're planning to work on, and that's definitely the right road to be on. You specifically mentioned insulation, but you may be losing as much (if not more) heat due to infiltration. There are many places infiltration can occur and a few small, obscure areas can leak a huge amount of heat on a cold, windy night. So if you can put every spare dollar and minute into getting the place buttoned-up, you're likely to see a huge drop in heating requirements. The other thing to consider is the condition of your current boiler - is it a newer, efficient unit that's been well-tuned by a good pro? The electric WH to eliminate Summer oil sounds like a good choice regardless; but you may find, after doing lots of good improvements, your best $$ choice may be to keep your current oil burner, depending on its age and condidtion. Then, after seeing how things go next Winter, perhaps a small pellet stove might complete your picture.

 

[R Mannino]

An updated oil system in that size home should only use around 650 gallons a year. Yes oil costs are high, but consumption can be reduced. Don't get me wrong, I have a wood burning stove as well in a 1400 sq ft house (Harman Oakwood)

 

[rowerwet]

I would keep the oil, after all it is paid for, go electric for the hot water (indirect oil hot water is a big waste) and add a pellet boiler that heats the oil boiler, that way if the pellets go out the oil will kick in. Also add a sidearm HX to the water heater to save on electric during the heating season

 

[EcoHeat]

mtbikerj - The plan you describe at the start of this thread is solid. More insulation is a good place to start.

A pellet boiler with a back-up electric boiler solves your one-flue issue. Electric boilers are also fairly inexpensive, easy to integrate, suitable for emergency back-up in winter, and a decent choice for domestic hot water in the summer (in conjunction with your Boiler Mate). The Boiler Mate can remain integrated with your system. In the future, you could replace it with an indirect HW tank that includes an electric element if you want, but that's certainly not a requirement if you have the electric boiler piped near the tank to minimize stand-by losses.

If you want to have sufficient pellet storage so that the pellet boiler could run a week or two without requiring a filling, a 1000 lb capacity storage unit would do the trick. If you're burning 2 bags per day while away, it would give you 12 days between fillings. Add an extension and you're up to 2 weeks.

Condensing oil boilers may become a viable choice for some, but the problem remains that despite their increase in efficiency, they are still burning oil. That low-sulphur oil is probably going to cost more as well. Oil is in an inflationary spiral, having risen 12.3% on average, annually, for the last 13 years.

Anyone considering a pellet boiler is invited to see a demo EcoBoiler set up here in East Walpole, Mass.

 

[mtbikerj]

Thanks everyone for all the advice. I've been on vacation and unable to respond on this thread for the past couple weeks.

I was able to get a hold of the history of oil purchases for the past 3 years from my oil distributor and I go through about 750 gallons per year, not the 1000. Regardless, I still want to get rid of oil altogether, mostly because I would like to use my flue for pellet or wood, but also because of price. Even if oil were to drop to lows of $2 per gallon from the $4 it is now, pellet would only be slightly more expensive in that case (not even considering that it would probably go down too because of transportation costs).

I've looked a little further into electric boilers now I think I may have an issue with the amp requirements as my home has a 100 amp breaker box. I'm still looking into it though. Thanks for all the advice.

 

[mtbikerj]

one thing that may help me though as I'm looking more into the electric boilers. the amp requirements are different based on the BTU of the furnace that I need. Since it's a backup (and only going to run when I'm gone and I turn my home heat down to something like 52 degrees). What size boiler would you think I need for this backup electric? If I can get a smaller unit, like 40K BTU / HR I might be able to swing it with the 100 amp service.

 

[ewdudley]

one thing that may help me though as I'm looking more into the electric boilers. the amp requirements are different based on the BTU of the furnace that I need. Since it's a backup (and only going to run when I'm gone and I turn my home heat down to something like 52 degrees). What size boiler would you think I need for this backup electric? If I can get a smaller unit, like 40K BTU / HR I might be able to swing it with the 100 amp service.

Using 'easy reckoning' as the old timers called it:

750 gallon * (140000 btu / gallon) * 80% efficiency / ((100 heating days) * 24 hour / day) = 35000 btu / hour average heat use

Supposing cold days use twice as much heat as average, we have a max load of 70000 btu per hour.

On paper heating to 50 degrees on a 0 degree day should use 50/70 times 70000 btu per hour, equals 50000 btu per hour.

(50000 btu / hour) / 220 volt = 66.61 amperes.

So if peak load is less than twice average load, and/or you can get by with lower than a 50 degree setpoint, and/or your coldest day is warmer than an average 0 degrees, and/or your current oil efficiency is less than 80%, and/or heat load as a function of deltaT is non-linear in your favor; a 40000 btu per hour electric boiler could get you in the ballpark.