# older HS Tarm



## Eric GK (Nov 10, 2007)

I am new to the site so thanks for having me.

We have an older (late 1970's) Tarm multi fuel (oil, wood/coal) furnace that we primarily use as back up to our woodstove. We get our domestic hot water through an indirect water heater.  Since the Tarm is only about 75% efficient, we are thinking about replacing the Tarm with an efficient oil fired furnace.

Is there a way to make the Tarm more efficient?

Should we keep the Tarm (just to have) or get rid of it?

Is there a way to tie the Tarm into the heating system (once the new furnace is installed) and use it as a wood boiler?

If I get rid of it, how much is it worth?...the thing weighs a ton, literally...would be fairly difficult to get it out of our basement.

Thanks in advance to all of these qustions


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## jdurant (Nov 10, 2007)

keep the tarm they build a quality unit. It is worth having in the long run. look at ebay to check out what the going price for a used boiler goes for.


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## Eric GK (Nov 10, 2007)

So, you think we should keep using the Tarm in its current function...even though we do not use the wood/coal option?


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## Nofossil (Nov 10, 2007)

Is the Tarm backup for just domestic hot water, or for space heating as well?

Part of the equation is how much you use it. If you're burning 100 gallons per year at $3.00 per gallon, the difference between 75% efficient and 90% efficient would be less than $50 a year. Might make you feel good about being efficient, but that's a really long payback on purely financial terms.

At 1000 gallons per year, the difference is more like $500, and gets closer to making financial sense.


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## Eric GK (Nov 10, 2007)

We use the Tarm for hot water (though we have an indirect fired water heater) and back up for heat. We primarily use a Napoleon wood insert for heat...the Tarm is used as a backup heat source for when we are away at work. We definitely use more that 100 gals. per year. I would say about 750 or so.

To be honest, I have never even made a fire in the Tarm...


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## Nofossil (Nov 10, 2007)

Relax - nobody's going to beat you up for using such a lovely piece of equipment as a -gasp- oil boiler.

On-demand hot water heaters appear to be a simple and very cost-effective solution - much more efficient than oil/indirect (which was the least expensive operating cost of any system when we built our house).

Rigt now, electric is pretty competitive with oil, and would almost certainly be cheaper in your case.

If you're adventurous, there are other schemes. I've seen an electric hot water heater that was heated by a woodstove via a thermosiphon loop. Needs a tempering valve to limit outlet temperature. The electric kicks in when needed, but very rarely during wood heat season. The HW tank needs to be near and above the woodstove for that to work, but there are plenty of other ideas out there.


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## Nofossil (Nov 10, 2007)

Maybe sell the Tarm and the indirect tank (I might take it myself) and use the money towards on-demand or conventional electric....


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## Eric GK (Nov 10, 2007)

I just the indirect water heater in so I don't think I want to eliminate that. I might call Tarm to see if there is any way to upgrade the Tarm. Realistically, I don't see myself using the tarm as a primary source for hot H2O and back up heat. My Napoleon uses about 3-4 cords of wood a year. Cutting 7-8 seems like too much. Plus, how efficient is the old tarm on wood alone? My wife is a bit leery...


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## Eric Johnson (Nov 10, 2007)

Used wood boilers don't have a lot of residual value, mainly because you can't tell by looking at them what condition they're in. But I'm sure you could get $500 or $1,000 for a Tarm, especially if you've never built a wood fire in it. Old technology, unfortunately, but as nofossil noted, a quality piece of equipment.

But I'd be inclined to keep it. Might be a good selling point if you ever decide to sell your house.


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## Eric GK (Nov 11, 2007)

Thanks for all of your help.

I think I may be inclined to keep it rather than pay the $200 to have it destroyed and taken out. I may get a new oil fired furnace, though. I just feel that I do not use the Tarm as it is intended - mainly as a wood fired.

I stillmay call Tarm and find out if their is a way to upgrade the old furnace to better efficiency as a oil fired unit.


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## webbie (Nov 12, 2007)

Since I owned Tarm USA for a number of years, I feel qualified to tell you that there is no easy way to increase the efficiency of an older Multi-Fuel.

The newer series (500) is a bit better than the older series (OT) - you can tell the difference because the OT has the wood loading door on the wide side, while the other has it on the end.

If you are not going to use it for the other fuels, I think you are on the right track by considering a more efficiency oil-only unit. Because we are in a bit of a wood burning "upside", you may even be able to get some reasonable money for the Tarm and have someone remove it (a rigger)...


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## Eric GK (Nov 12, 2007)

Our Tarm is a 500 series. Turns out, the baffles are burned through so I think if we replace them, out efficiency for oil should at least be in the low-80's. I think we will keep it for now. We may find a desire to burn wood in it if oil keeps going up. At least we have some options available to us.


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## webbie (Nov 12, 2007)

500 Series is much better than the OT with oil since it has a full set of firetubes, etc.

Yes, there was a problem with those separation baffles - the new ones might come with a kit that contains refractory protectors which install below them.


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## Eric GK (Nov 12, 2007)

Spoke to Tarm and they did a nice job clueing me in. The heating guy that did the service didn't though. He just said we needed a new furnace!

I'll ask if the have the kit you are referring to. Thanks for the info. I have learned a ton over the past few days.


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## mikeyny (Nov 16, 2007)

I have been using a 500 for 4 yrs now. I removed it for the previous owner because he used it primarily with oil. It was very inefficient. The wood coal side works real well for me. I would not even consider using it with an oil burner unless  the oil was for backup only. Apparently they were originally designed to operate primarily on wood and the oil would kick in at the end of the heating cycle when the wood fire goes out if your not home or in the early morning hours before you get up. I think they are a great unit if used properly.


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## Eric GK (Nov 17, 2007)

That's the stuff that I keep hearing: great for wood/coal but poor performance on the oil. So, I think we will go with a Buderus boiler and keep using the Napoleon for our main source of heat. I will keep the Tarm so I can reconnect it when oil gets to $10.00 a gallon or WWIII begins - -whichever comes first.


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