Combustion tunnel eroding on Tarm Excel

I have heard of that happening. That ceramic part does have to be replaced at some point over the life of the boiler. Contact Bioheat USA to find out how much a replacement costs. I think it is fine to run for a while as long as the pieces fit snuggly. Chris from Bioheat is on this forum and will likely pickup on this thread at some point. Good luck with it!

Can you take a picture of what you are talking about? The ceramic combustion tunnel, I thought was one piece.

LarryD

It's probably covered under a pro-rated warranty. Check it out!

I get about 3 years on the refractory in my Tarm boiler. I usually need the two top firebricks, the bottom combustion chamber, the flat piece at the front of the bottom door, and misc gaskets. I think it was about $500 last time I bought them. According to Tarm this is normal wear and tear. This is the only problem I have with the boiler. It is about 10 years old.

Brialin said:

I get about 3 years on the refractory in my Tarm boiler. I usually need the two top firebricks, the bottom combustion chamber, the flat piece at the front of the bottom door, and misc gaskets. I think it was about $500 last time I bought them. According to Tarm this is normal wear and tear. This is the only problem I have with the boiler. It is about 10 years old.

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I am on my 4th season and have not noticed any significant wear on the parts you mention. I will have to keep an eye on it though. From what I hear this is a common issue among gasification boilers and just part of running them. Brialin - How much wood are you burning each year? The wear and tear on this stuff is often measurable by the amount of cords burned. Just curious...

If it's like the tunnel in my solo 40, it's about $100. I just replaced mine, it lated almost exactly 1 year before the front end broke into 3 pieces. The replacement cracked there as well, after about 3 weeks of use. I assume it was a flaw in the refractory, I need to send the broken pieces back to Bioheat for their inspection. I've been too busy to pull them out over the past week and send them back. The rest of the refractory is holding up well, it's just the tunnel stone thats giving me fits. I have noticed the broken pieces seem to cement themselves in with ash if you are careful not to disturb them during clean out.

FWIW, I burn about 15 face cord of wood per year. The wood is mostly elm with a little sugar maple and hornbeam mixed in.

I burn about 12 cord a year. Half of it is pine and hemlock which really burn hot. I used to get small blocks of pallet wood for free but I would burn the refractory material out in one year. The wood burned too hot. The refractory was super red. If I just burned hardwood I probably would use 7-8 cord.

Don't know if it would be feasible on the Tarm or not, but some users have made molds to make their own replacement refractories out of refractory cement or other similar materials - note that some of these materials are pretty expensive in their own right, so it can be a debate as to how much savings you get...

Gooserider

I thought about making my own refractory brick but I think is is too complicated because there are air passages molded into the refractory.

Yup, as indicated, the tunnel stone is a consumable part and will need to be replaced periodically. Normal life is expected to be about five years and the part is covered under a three year pro-rated warranty. Cracks and erosion are normal and the stone does not really need to be replaced until it is really falling apart. Give Brian in parts a call (ext 103) and he will take care of you. Chris

Just a wondering question here ? I know my Solo 60 is over sized , and with the 1-1/4 pipe to and from the storage and the zones I cant get the water to move fast enough to cool the boiler and so it cycles . ( In fact I can almost Time it as it burns for about 10 minutes then kicks out for about 30 , until the wood is consumed ) But I am still on the original set of refractory and am on my 8Th year . Now could it be that all this trying to keep the boilers gasifying and burning continually and not kicking out cause the issue of these refractory actually burning up ?
Now I am just wondering on how efficient it is to be burning up a 500$ set of refractory in say 3-5 years verses say 5-10 My thoughts here is so maybe I don't get the mostest out of my wood and it cost me the cutting of an extra 1/2 cord a year big deal I am by far more efficient . ( Or is my thinking wrong )

Webie, I have a 60 w/ 1000 g storage and my boiler is over sized. I burn mostly to storage. There many variables that influence the way all of our systems work but it seems you're in idle a lot. I have only been burning with this stove 2 years and added storage this past fall so I'm still making small adjustments but am happy overall.
Two things you might want to look at to stay in gasser mode more would be to slow down the water through the boiler. I have my Grundfos 15-58 on speed 2. If you run water to quickly through your boiler you don't necessarily extract more heat. The other area to look at is making small adjustments to the Termovar mixing valve. Input side #1 (hot water from boiler) needs to be (for me) somewhere 1/2 and 3/4 restricted. When you narrow in with the tremovar restriction, a small adjustment makes a big difference.
This is assuming that the tremovar is not stuck or something.

RobC said:

Webie, I have a 60 w/ 1000 g storage and my boiler is over sized. I burn mostly to storage. There many variables that influence the way all of our systems work but it seems you're in idle a lot. I have only been burning with this stove 2 years and added storage this past fall so I'm still making small adjustments but am happy overall.
Two things you might want to look at to stay in gasser mode more would be to slow down the water through the boiler. I have my Grundfos 15-58 on speed 2. If you run water to quickly through your boiler you don't necessarily extract more heat. The other area to look at is making small adjustments to the Termovar mixing valve. Input side #1 (hot water from boiler) needs to be (for me) somewhere 1/2 and 3/4 restricted. When you narrow in with the tremovar restriction, a small adjustment makes a big difference.
This is assuming that the tremovar is not stuck or something.

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Thanks RobC for the information , I have been all over the plcae with the valve and I am set up about the best I can be right now . I am running a B&G nrf-25 3 speed on it right now on 2 . You are correct even when I run on 3 I only gain a few minutes of time . Return water temps after the mix hold pretty well between 154 and 164 depending on tank temp .
Dont get me wrong I am happy with the performance , All I was stateing was the fact that maybe there needs to be alittle rethinking here on economics versus 100 % efficiency.
My statement was are the guys chewing up the refactory super fast because they are always on a continued gasification burn verses mine that has a chance to cool inbetween .

The high heat I think does affect the refractories. I remember reading that they get softer with age, or some thing... But on the other hand if your at idle that much it doesn't seem that your running super efficiently either. For example if you were to burn for 30min and idle for 10 then you would be gassifiing for sure. But to burn for 10 minutes it doesn't seem you'd be getting the refractory that hot to get maximum effect for very long ?
What happens down stream going to storage ? Is it pressurized, HX or tank with coils. If your 1.25" all the way it seem like you are choked up someplace ?
If I burn a full load (filled to 1/2 way up loading door) it takes about 3 to 31/2 hours to burn down. That's almost one straight burn.
Any way I did get your point about damaging the refractories and replacement cost vs. having to throw in a bit more wood.
Rob

RobC I am thinking my chokeing place are the 3 -3/4 coils that are in the unpressurized tank that are slowing the flow down, or its the actual thermovar itself that is slowing it . I also run glycol here to and I have heard and read all kinds of things about it in heating systems which maybe haveing an negeative effect on things .

webie said:

RobC I am thinking my chokeing place are the 3 -3/4 coils that are in the unpressurized tank that are slowing the flow down, or its the actual thermovar itself that is slowing it . I also run glycol here to and I have heard and read all kinds of things about it in heating systems which maybe haveing an negeative effect on things .

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Glycol is pretty much bad stuff, well worth avoiding if you can, as about the only good thing about it is that it's less likely to freeze... Granted that this can be an important virtue in some cases, IMHO it's worth avoiding if possible...

1. It's expensive... Water costs far less, even if you have to treat it.

2. It's harder to pump than water.

3. It does a less effective job of transferring heat than water.

4. Over time it breaks down and can become corrosive.

5. Spills can be environmentally problematic.

The only time I'd suggest using it is if there is a high risk of freezing if the wood fire goes out, and there is no easy way to do alternative heating that can at least keep things above freezing...

Gooserider

Here's a site that has tons of tech info. comfort-calc...... if you go to their tech area you can get all the data one could want. Then to hot water boiler.... and that get's you to here http://www.comfort-calc.net/tech_area_index.htm#HWB
There are others on this site that do math better than I.... Plus this should be it's own thread at this point....
However, the glycol isn't helping but can't be your main issue. Nor would the tremovar be the main issue. So that leaves the coils and how their piped up.
1 X 3/4 copper can carry 40,000 BTU @ 4GPM with a 20 F differential
1 X 1.25copper can carry 160,000BTU @ 16GPM w/ a 20 delta T. If you read the stuff on comfort calc..... they talk about velocity, and how that factors in. To fast you don't leave the BTU's behind they don't have time to transfer, Same if you go to fast.
Back to your system, here is some coil info and transfer rates http://www.stsscoinc.com/Products_HeatExchangerCoil.aspx , I don't know if you DIY coils but this should give you and idea of how many feet of copper coil you need to have submerged.
You said you had low return water temps which is puzzling ???? How about the way you have the 3 coils hooked together ? The way you have the supply and return piping allow for the equal distribution of the water through all 3 coils ? In the STSS pict with 2 coils you can go from 1.25" to a 1.25" X3/4 X 3/4 tee and keeping all pipe runs the same the water will flow about the same. With 3 coils it's not as easy to keep the water balanced in 3 coils flowing the same. Could water be favoring 1 coil, there by giving you low return water but not drawing off all the BTU's expected of the 3 coils ?
Any of that help ?
Rob