Converting Home From Oil to Wood Boiler

[hiker88]

Hi,

I've been reading the forum for a few days and I'm hoping I can get some advice on my situation.

First, my home is a colonial constructed in 2006. It is my wife and my first home. The house is about 2200 square feet with baseboard heat. I have an oil burner with a direct vent (not a power vent) and the house doesn't have a chimney. We are a family of 3 and we burn about 650 gallons of oil a year. My wife and I both work, so the house is kept at 60 m-f 7-5 and then between 66-68 until we go to bed at which time the heat goes back to 60. It's turned up on the weekend of course too. I put a family room in the basement last spring and at some point I will add a zone for that room which will probably bump up my oil consumption a little bit.

The reason I am looking at options is mostly due to my current setup and issues I have. Luckily, I have a service plan because I have to call the oil company to come out and get the burner going 3-4 times a year. I have a Beckett burner and it is very finicky. It seems any time the seasons change, the fuel\air mixture gets off and plugs up the system. I have a pretty good oil company and when I asked them about replacing the burner, they basically said, we could sell you a better burner (for about $1600) but what you really need is a chimney. Their senior tech took hooked a device up to my direct vent and showed me how I basically have no draw.

Well, my though is that if I am going to put in a chimney, I want to do it in such a way that I have options.

I'm interested in a wood boiler due to my access to cut-able wood and my desire to reduce my dependence on oil. However, I think it would probably cost about $15,000 to go from my current situation to having a chimney, and a boiler with storage.

My question here is, could I do things in stages? For example, have the chimney installed and my oil burner hooked to it then, add 1000 gallons of storage (just putting out an approximate number for now) which would be heated by my oil system and then in a couple years buy the boiler and make my oil burner the backup?

My oil guy explained that right now I basically have the most inefficient system you could come up with for heating hot water in the summer. He explained that my system is proably about 75% efficient in the winter, but in the summer he estimated my efficiency is probably somewhere around 20%. As it is now, if you turn on the hot water to wash your hands, more often than not, the furnace will come on. So, that is why I am concerned about just getting a chimney, if I do that, it's true that the oil guys won't have to come out as much, but I haven't done anything to deal with the inefficiency of my current setup. I'll just have a well running inefficient set up... My tech explained how I could convert my oil burner to a "cold start" system and add a "boiler mate" I think it was called but I think that was only around 60 gallons of storage or so. My thought is that I would add the kind of storage that a wood boiler would need in the future.

Your feedback is appreciated. Thank you.

 

[willworkforwood]

Welcome to the forum. You have a lot going on there, and a number of possibilities. The one thing you don't want to do is heat storage with your OB. Storage is used with wood boilers because they modulate by idling (smoldering), which isn't efficient. They are most efficient by running full-bore, start to end of the load. But that's normally way too much output too fast - the storage is there to capture everything for controlled use later, over an extended period of time (think of it as a battery). A fossil boiler shuts down and is not burning oil when there is no call for heat, so heating storage is just a waste of energy. Regarding your OB situation, would it be possible to change the direct vent to power venting? That would probably be a major savings (versus a chimney) if you could do it. I would take care of the OB first - you may find that with a well-running OB making DHW efficiently, you might only need a cat wood stove for heating (just one of the possibilities). Other questions relate to heating with wood. Have you done that before (i.e. know about the work, smoke, mess, etc.)? Assuming you know about wood and really are serious about moving forward with it, you may need to make one decision now. If you can't (or don't want to) power vent the OB, and need to add a masonry chimney, then your decision will be the $$ for a separate flue. You would need a separate flue for either a boiler in the basement, or a wood stove (basement or main floor). But there is also the outbuilding boiler possibility. Lots of things to consider - others will probably offer additional thoughts. Good luck with it!

 

[Clarkbug]

I havent ever heard of a direct vent oil boiler before, but then again Im new to most of this as well, so thats not overly surprising. (Also means I would wait for the real experts to show up)

My thought would be to install a chimney with two flues in it if you are going to put one up at all. That way you have one ready to go in the future so you can run wood and keep your oil boiler as a backup ready to go. Most places wont let you share a flue between two boilers, and its nice to keep the oil around in case you want to travel during the winter.

I would not add the 1000 gallons of storage right now, since it wont really help you out on the oil side of things. You will see some efficiency gains over the long haul in the winter months, but it wont help you on the domestic side, and you should save the money for down the road when you get a wood boiler. (Others may have more input here...)

I think it would be a good idea to install a boiler mate or a super-stor. That 60 or so gallons is for domestic hot water storage, not heating hot water storage. So, your boiler will fire up in the summer, heat the 60 gallons, and then turn off. It will help prevent the short cycling of your current system. If it is set up as separate zone with priority (which is my guess as to how your installer would do it), you can then use the wood boiler to heat domestic as well.

So I would go in this order:

1. Chimney w/2 flues.
2. Boilermate domestic hot water heater on separate zone.
3. Wood boiler of your choice and storage tanks.

Good luck, ask lots more questions, and welcome to the forums!

 

[hiker88]

Thank you for the considerate responses. I have a couple masons coming next Mondayfor an estimate on a double flue chimney. I think that will be good info to start with.

Please excuse my lack of knowledge, but one thing I don't understand is the role a boiler mate would play if I go ahead with with a wood boiler with storage. I guess I thought that both dhw and heat for the house would coil through the storage connected to the wood boiler?

My hope was that I would run the boiler everyday in the winter for heat & hot water, and then in the shoulder or summer season, only have a fire every few days as needed to heat up the stored water. My concern is that the quality indirect hot water heaters for my oil burner are quite expensive ($2,000 approximately) for something with a life time gaurentee, and I can't afford to invest in that now if it will be unnecessary if I have a full wood boiler set up within the next two years.

If someone could clarify for me the role the boiler mate would play in a wood boiler with storage setup I'd be grateful.

Thank you/

 

[Clarkbug]

Running your DHW through the wood boiler storage is one option that you can use, and you are right, you can have a dual purpose storage.

My response was based on the idea that you would set up a boiler mate like a zone on your heating system. When that "zone" calls for heat, it would be provided from your heating system. Depending on what you have available, that could be your oil boiler, the wood boiler, or the storage connected to the wood boiler. A boilermate is something that could be utilized on your existing system, as well as with the wood boiler.

You will need some type of heat exchanger to produce your DHW from the boiler system, so I guess thats the next thing to decide. You can install a coil as you mentioned , or you can use a flat plate or sidearm with pressurized storage.

The idea of using the boilermate was only that it would be something that works with both systems, regardless of what type of storage or piping you go with in the future. I do agree may not be the most cost effective way to do things, but it does keep them relatively straightforward.

 

[ewdudley]

...
You will need some type of heat exchanger to produce your DHW from the boiler system, so I guess thats the next thing to decide. You can install a coil as you mentioned (probably would only work with unpressurized storage), or you can use a flat plate or sidearm with pressurized storage.
.....

Here's a coil-in-pressurized-tank solution: (post #5)

https://www.hearth.com/econtent/index.php/forums/viewthread/72019/#835793


And here's a roll-your-own upside-down 'boilermate' that serves to bring heated water from storage or from a backup fossil-fuel boiler to a central hydraulic separator/DHW circuit heater/hot tub circuit heater: (post #3)

https://www.hearth.com/econtent/index.php/forums/viewthread/66601/#760078

--ewd

 

[Clarkbug]

My above post, edited per the wisdom of Mr. Dudley.

 

[jimbom]

I am wondering what it is about a five year old installation that basically has no draw in the vent. I am sure you have run that to ground, but it tickles my cobwebbed brain.

Is the house a better chimney than your flue? If so, it will still be the case with your new masonry chimney. If the house is tight then this is probably not an issue. Have you checked around for air leaks and foamed everything that penetrates the building envelope?

Wonder if during the 'season changes' something happens to put your boiler room into a temporary low pressure circumstance? New wind direction etc.

I don't have a boiler, so this advice is from that vast swamp of ignorance between my ears. There are some islands of knowledge, but it is mostly swamp. Good luck.

 

[flyingcow]

My house has an oil boiler with an Amtrol boiler mate. I had installed a wood boiler plus 820 gals of unpressurized storage. I went about a month running my DHW thru the boiler mate(oil was off line). Than, the DHW coil was installed in tank. Running thru the boiler mate used up more heat out of the storage than direct from the tank.