Harman VF3000 summer burning?

Hi Again!

I know some people hate it but for me half the fun at looking for a boiler is the research. I am getting closer but on my way home from work yesterday I drove past a Harman dealer and thought I would stop in to look at a VF3000. The dealer's house was next door and he has a VF3000 installed with the add on oil burner. I asked him how he liked it and if he used it for DHW and he said yes but he runs it with the oil in the summer. He shuts the coal off this time of the year due to drafting problems. Personally part of the reason to switch to a boiler for me is to make DHW all year if not I would just install a stoker. Its simpler to install and cheaper. Anyway, my question is are there any VF3000 owners running there boiler all year and heating DHW? If not is the reason you are not doing it because of poor draft, excess heat in the house, or just too much work and easier to heat DHW with electric, oil, etc for the summer. Thanks again for any help.

For me, it's all of those reasons. Excess heat in the house would add to my A/C load, poor draft and I need a break from the girly man routine of shoveling 250# of coal and emptying the ashes. With all the $$$ I save heating, I don't feel too bad about using the water heater in summer. Remember in winter, you hot water is "almost" free.

if a chimney has enough draft for an oil boiler, should it also have enough draft for a coal boiler?

or have I overlooked something that I'm about to get reprimanded for?

I think may have already seen my post here coal consumption for dhw question

Still some what a rookie to Coal stoker boilers, but I'm very happy with my VF3000. Installed it myself which I love to brag about

Well Beatle I don't know a lot about coal either but I don't think just because 1 unit vents well in a chimney another one will too. An example is my oil boiler vents into a 12x12 flu just fine but my wood stove would not work well in the same flu. It has to do with the area of the flu. The wood stove is designed for a 6inch round pipe. If you calculate the area of a 6" circle vs my 12x12 flu that is a huge difference. I just don't know how much the blower on a coal stove influences the draft. I would think it would have to help because the air from the combustion blower has to go somewhere.

Hello Hunt

I use my VF3K for DHW and have not had problems with drafting during the summer. I have an insulated SS chimney, and my draft will fall to about .02" during the warm weather. While this is below what Harman reccomends I haven't had problems with it.

I have a CO monitor in the same room with the boiler so If there were spillage, I would know about it, besides the fact you can readily smell coal gas.

Coal usage during the summer months is about 12# per day so the hopper is good for at least a week. I empty the ashes once a week during the warm weather, they typically fill a supermarket sack and I put them out with the garbage . At $200 a ton, it works out to about $1.20 a day, or about 1/3 gallon of oil at today's prices. Can't beat that.

Thanks for the unfo Highlander. Is the SS chimeny a currugated liner. That is what I have for my wood stove but 6 inch. Guess it would be 7 inch on your Harman.

Hunt, my chimney is a solid pack insulated type made by Simpson, Dura Vent, they are typically used with woodstoves, but it is rated for burning coal. It is a 7" since that is what the size of the breech is. 6" would probably work fine, but I was warned that the building inspector would want to make sure that the chimney wasn't smaller than the flue opening, and sure enough, that was about all he checked.

As an aside, my coal usage for the last couple of days has been between 10 and 11# per day, a bit better than last year. I attribute that to the variable speed control I added which lowers the blower speed substantially when the unit isn't stoking. This limits the excess air being pushed through the boiler and lets the coal burn more thoroughly.


Bill A.

I know the specs for the VF3K boiler say the flue opening is 7" but 7" pipe is too big for the thimble. Also on page 13 of the installation manual it says to use 6" vent pipe. Mine is hooked up with 6" pipe and works fine.

I know nothing about coal boilers but I cant imagine that, unless you have a large family taking many showers, that it would be financially worthwhile to run a coal boiler all summer long for just DHW, not to mention the heat! How about a tankless water heater instead? (I'm thinking of buying one when my regular water heater is about to go. If I install it myself I can probably get away for around $800.00/installed.

Well Devil I guess it depends what you pay for DHW and how much work you are willing to do to save money. From what I read the high side coal useage for making DHW is 12#/day so x 7 days x 4 weeks x 4 months = 1334# for 4 months of DHW. Coal here is $160 ton so 0.08/lb so to make DHW for me for 4 months would cost $106. At 3.50 gallon oil I could buy 30 gallons of oil for $106 which would not be enough to make DHW for me for 4 months. I doubt if an electric water heater would do any better. I also looked at the tankless water heaters but I think you need to go propane to make them work unless you install 1 at each point of use but that is just my opinion.

huntabsarokee wrote:Well Devil I guess it depends what you pay for DHW and how much work you are willing to do to save money. From what I read the high side coal useage for making DHW is 12#/day so x 7 days x 4 weeks x 4 months = 1334# for 4 months of DHW. Coal here is $160 ton so 0.08/lb so to make DHW for me for 4 months would cost $106. At 3.50 gallon oil I could buy 30 gallons of oil for $106 which would not be enough to make DHW for me for 4 months. I doubt if an electric water heater would do any better. I also looked at the tankless water heaters but I think you need to go propane to make them work unless you install 1 at each point of use but that is just my opinion.

Tankless will work off natural gas but my main problem is my tank heater is only a few years old, It's just my wife & I, & I've heard tankless requires more work (flushing out, etc) than the tank type. I figure i costs me about $40.00/month for hot water so I'm in no rush.
I was just reading the other thread on this subject & was unaware that boilers could be run with such low fires & on so little coal in he summer. (Hey...I warned you I knew nothing about boilers! ) No problem with the chimney draw when it's in the 90's outside?

Well I don't claim to know anything about the boilers just what I learned in a short time reading here. There are quite a few people that run them all summer but I also had doubts about the draft. I recently talked to a friend whose mom runs coal all summer long in her house as well as in 2 of her apartment buildings. My friend does light maintenance work on the boilers and says on occasion they do go out when its really hot and humid but its rare. I hope to get a boiler and find out.

huntabsarokee wrote:My friend does light maintenance work on the boilers and says on occasion they do go out when its really hot and humid but its rare. I hope to get a boiler and find out.

& what happens to the CO when the draft fails & starts to back-up into the house? Not worth the hassle for me.

Devil5052 wrote:I know nothing about coal boilers but I cant imagine that, unless you have a large family taking many showers, that it would be financially worthwhile to run a coal boiler all summer long for just DHW, not to mention the heat! How about a tankless water heater instead? (I'm thinking of buying one when my regular water heater is about to go. If I install it myself I can probably get away for around $800.00/installed.

I have an indirect hot water heater that can be heated by either my coal or oil boiler. Last summer I heated my hot water exclusively with oil. I have a running time meter on the oil burner and average oil consumption was 0.64 gallons per day. This summer I will use coal and expect it to be significantly less costly. Family of two, using lots of hot water. Wife's a wash it hot and often clothes washer.