Anyone still using an HS Tarm OT-35 boiler?

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Old 03-26-08, 05:18 PM
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Anyone still using an HS Tarm OT-35 boiler?



Mine is still going after all these years and I'm starting to wonder if people are trying to make them more efficient these days?

I installed a BECKETT 7512 HEAT MANAGER on mine last year, to limit short cycling of the burner and it seems to be working pretty well.

Anyone know of any worthwhile mods that might be a good DIY job?

PS: That tape on the door handles is to keep noisy folks from wasting heat. Plus, I have not burned wood in 3+ years.

Thanks,
 
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Old 09-03-08, 01:28 PM
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HS TARMS Ot-50

I currently have a OT-50 model and have been using the oil-fired option for past five years. I believe the previous owner used oil for the 12 yrs they owned. The original owner, I was told, fired with wood and/or coal. I am seriously thinking of using with wood this winter but not totally comfortable doing as I do not know if all the parts/set-up is there to use as wood fired.
 
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Old 09-03-08, 02:47 PM
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If you look inside the doors, you should be able to tell if
you have a wood or Coal Shaker grate.

If you don't have a grate, you are out of luck.

The other item you will need it the arm & chain that is connected between the lower air-intake flap and the temperature control (black knob) in the upper right hand side.
As the water gets colder, the arm lifts up and allows more air
to get to the firebox. It gives great control over the max temp.
(if you don't have the arm, I can give you the dimensions so you can make one).

Oh yeah, check you chimney & the stove pipe hardware behind your boiler. It should be clean and in good shape.

Also check your zone check valves. See if they have a free-flow On-Off knob. Free flow allows you to burn wood and not need any AC power to for the pump(s). It's slow, but it will heat your home during a power failure..
---

I've made my Tarm a bit more efficient. I noticed that the top cover always felt warm to the touch. The insulation inside the top cover isn't the best.
So, I got a roll of layered foil/air bubble installation at Lowes, pulled off the top cover, and rolled out a few layers on top of the steel boiler top. Later I checked the top and it felt COLD!
I also used some stick-on insulation over some of the gaps in the rear of the top-cover where the domestic hotwater pipes exit. I used better pipe insulation on the pipes going in and out of the boiler too.
The rate of heat loss has dropped drastically.

I've also trying out a 1.0 GPH burner tip and it seems to work fine so far. (I'll know for sure when I do the fall maintenance).

This summer, we have been only using the Tarm On-Demand. When we want some warm water (170f), we turn on the switch in the kitchen and let it run for 20 minutes (1/3 gal)..
We end up with enough warm water for 2 people for about 24 hours.
Our 275 gallon oil tank has dropped by about 1/8 since April..

If you would like any more info or pics of the setup, please let me know.

Cheers,
Rich
 
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Old 12-17-09, 04:33 PM
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Originally Posted by XRing View Post
If you look inside the doors, you should be able to tell if
you have a wood or Coal Shaker grate.

If you don't have a grate, you are out of luck.

The other item you will need it the arm & chain that is connected between the lower air-intake flap and the temperature control (black knob) in the upper right hand side.
As the water gets colder, the arm lifts up and allows more air
to get to the firebox. It gives great control over the max temp.
(if you don't have the arm, I can give you the dimensions so you can make one).

Oh yeah, check you chimney & the stove pipe hardware behind your boiler. It should be clean and in good shape.

Also check your zone check valves. See if they have a free-flow On-Off knob. Free flow allows you to burn wood and not need any AC power to for the pump(s). It's slow, but it will heat your home during a power failure..
---

I've made my Tarm a bit more efficient. I noticed that the top cover always felt warm to the touch. The insulation inside the top cover isn't the best.
So, I got a roll of layered foil/air bubble installation at Lowes, pulled off the top cover, and rolled out a few layers on top of the steel boiler top. Later I checked the top and it felt COLD!
I also used some stick-on insulation over some of the gaps in the rear of the top-cover where the domestic hotwater pipes exit. I used better pipe insulation on the pipes going in and out of the boiler too.
The rate of heat loss has dropped drastically.

I've also trying out a 1.0 GPH burner tip and it seems to work fine so far. (I'll know for sure when I do the fall maintenance).

This summer, we have been only using the Tarm On-Demand. When we want some warm water (170f), we turn on the switch in the kitchen and let it run for 20 minutes (1/3 gal)..
We end up with enough warm water for 2 people for about 24 hours.
Our 275 gallon oil tank has dropped by about 1/8 since April..

If you would like any more info or pics of the setup, please let me know.

Cheers,
Rich
Hi Rich ; I was searching the web and came across your post on the Tarm OT 35 furnace . I wonder if you would be so kind to respond to a a question or two . I have a Tarm OT35 ,which dates back to the mid 70' s , and have burned oil most of the time . Recently I started burning wood and have found it much more comfortable . However , I have noticed that when burning wood , I am having difficulty keeping the water temperature at 200 degrees . I am stoking the wood regularly , and not over stacking the pieces . I keep the flap door a jar to allow more air into the box but often times I must use the oil to raise the temp to 200 . I had the person who installed the unit years ago look at it today and he said the furnace look great ; no mechanical problems . He felt it was just very cold here in Vermont and I needed to open the flap more or the ash door to allow more air into the unit until the temp got to be 200 . Can you please give me your opinion ? TIA , Ralph
 
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Old 12-17-09, 07:19 PM
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Hi Ralph,

I have not burned wood in about 20+ years, so I don't recall a lot on increasing the heat.
It might be a matter of the draft and the fuel you are using.

If you have the chain set up to pull the flap door (air input) open, until it hits 200 F, then that's about all you can do.

Also, if you have a good draft, then you can set the inside flap
(damper?) to let the heat pass more surface before getting to the flue.

One thing I have noticed using oil, is having the boiler set to 200 F, wasn't that much different than using 180 F.
And, you probably know that there is less heat losses when you run the system at lower temperatures.
IMHO, it's not necessary to run the Tarm at 200 deg..

Cheers,
Rich
 
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Old 12-18-09, 08:13 AM
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Thanks , Rich . I'll try lowering the water temp to 180 . I have a feeling it's the wood . A few weeks ago , I had no problems with dry as a bone wood , aged in my basement for 18 months . The wood I'm using now is about 9 months old dried outside and very heavy . I really appreciate your advice .
 
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Old 12-20-09, 02:00 PM
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Found the users manual

It says to use 200, if you are burning oil or gas for a long period of time. With a low limit setting of 180 & Cirulator setting of 140.

For wood:
High limit 165
Low limit 160
Cirulator setting 140
 
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Old 12-24-09, 04:19 PM
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Smile Wood drying rack for the HS-TARM OT-50B

I'm still using my Tarm boiler to burn about 6 cords of wood each year. I get so much heat from the boiler that I built a wood drying rack and use the excess boiler heat to dry my wood in the basement. It works great and I can dry a cord at a time.

If anyone is interested, I'll add some details on how I built the drying rack.

Mike
 
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Old 12-25-09, 08:14 AM
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Not me,

I'm trying to get away from burning oil or solid fuel.

The heat pump is the way to go..

Sanyo 24KHS72 AC/HP DIY install project - EcoRenovator
 
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Old 01-12-10, 11:43 PM
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i have a tarm ot-50 it was never winterized and it is now frozen. Can i use the wood to un-freeze it and then see it if will work with the oil heat?
 
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Old 01-13-10, 07:55 AM
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Wow!

The HS Tarm is made out of steel, so there may be some flex
to the boiler. Maybe it hasn't cracked..
But you may have some leaks in your plumbing.

I would start off with some low heat and slow bring up the
the temperature, to avoid any hot spots where you get a
steam pressure built-up while the expansion-tank still
has ice in it.

Maybe you could go real slow by sticking using a small
(1200 watt) space heater to feed warm air into the
clean-out door.?.

If you have 800 pounds of ice in there, it's going to take
a lot of BTUs to bring it back to a liquid state..

If you do have cracks in the boiler, it can be repaired.
You just need to find someone with a MIG welder.

I had a bad install done and water leakage caused a major
rust out on the lower backside of my boiler.
We cut out the rusted area and welded in a new section of 1/4" steel.



Took all day and cost me about $400 for the repair..

But to have it cut up and removed was going to cost over $1,000!
And then I would have to buy a new boiler!
 
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Old 03-23-10, 11:39 AM
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Well, I stubled on this thread looking for information on my HS TARM boiler. I have a tarm 504, been using it for 20 years or so. I burn every winter, 8 to 10 cords a year. No problems at all except for creosolt buildup... I think its due to the fact that the boiler burns hot enough where I have to cut the draft down... ANYWAY, I have to replace the grates at the bottom. The close ones to the door are okay, but how the heck do you reach the back ones? Is there a secret door somewhere to get access?? Thanks!! Paul
 
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Old 01-17-11, 08:44 PM
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More info TARM OT-35

I own two of these as well as an OT-50.

As previously pointed out, renewing the insulation is important for overall heat retention but for those of you who are interested in more efficiency from the WOOD side of the boiler I made these two simple modifications:

1) On/Off toggle switch at the oil burner. When burning wood we toggle the oil burner off (you will understand why in a minute). The toggle needs to be at the burner because the rest of the boiler needs to operate as usual, we are only cutting out the actual oil burner.

2) Wood Stove damper in the stove pipe from boiler to chimney. This helps control the rate of burn and also prevents energy loss by restricting heat loss up the chimney. For those of you who are familiar with wood stoves, this is standard knowledge. If you are not familiar with the vent/damper combination for controlling wood stoves then Google 'wood stove vent and damper' for more info

You cannot use a damper when the boiler is on oil burn, the flue needs to be completely open for the TARM to operate properly and to prevent backup of exhaust fumes into your living space. Hence the toggle switch for the burner: when we are at home and using wood, the oil burner is off and the damper is in use: when we are going to be gone for an extended period the oil burner is on and the flue is fully open. With the flue open you can still use the wood side of the unit as usual (handy for leaving a wood fire going and returning home to oil fired heat).

Another thing we did was to pipe the hot water coil (tank in OT-35s that have not been upgraded) directly into the supply side of our electric hot water. The water heater never calls for electricity because of the supply coming from the TARM and acts as an auxiliary insulated storage tank thus providing us with 80+ gallons of hot water when the TARM is in operation. Because the electric water heater stays in the 'on' mode, it automatically takes over when the TARM gets colder (wood only operation) or when we shut the TARM off for the summer.

If anyone would like pictures of one of the OT-35s in operation I would be happy to email them.

All the best
 
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Old 12-18-11, 07:51 AM
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I have one . I am the 3rd owner of the house built in the early 70's . I burn primarily wood and back up with oil. My ? is I am getting no heat on the 2nd fl. The rest of the house is fine . The zone valve has been replaced . My HVAC guy says the system needs mor H2O . (lines have been bled ). I can't find any "insource " for fresh water . Any ideas .
 
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Old 12-18-11, 09:45 AM
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Wayno, as the 3rd owner, are you saying that this is your first winter with the system? or do you have 'history' ? i.e. do you know if it EVER worked to heat the 2nd floor?

Is there a PRESSURE gauge on the system? If so, what is the reading?
 
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