Tarm without tank - maybe add later

[MrEd]

Hi folks...Newbie here.

Hoping to get a Tarm Solo very soon, but as you are all well aware the tank almost doubles the cost of setup, so my plan is to get by without it for as long as I can. I've read thru a lot of the archives and it seems an awful lot of folks start without a tank and end up getting one - I am wondering if there is anyone that doesn't have a tank, and is happy to keep it that way for the time being?

The tarm is roughly $7500, the tanks brings it close to $15,000 which is a huge incremental cost. What I don't know is if what percent of my oil I will save with just the boiler, versus the boiler with tank. I use about 1100 gallons of oil per year (thats with a wood stove already saving me 900 gallons). If the first $7500 investment saves me 90% of that oil cost, then that tank investment doesn't make a lot of sense...on the otherhand if the boiler-only solution saves me just 50% of my oil cost, and the boiler+tank saves me 100% of the oil, then the story becomes more compelling....anyone shade any light on this for me?

Also, I am really struggling with the in-the-house versus the in-the-woodshed choice. In either case, (if I get a tank), the tank would be in the basement. Question is, what is the difference in plumbing setup (assuming no tank) of an inside the house versus in the basement setup? Since the outside boiler would need anti-freeze, I assume the setup would be different.

last question for now - besides the cost of the boiler, what should I budget for miscellaneous parts (if I do it myself) or for parts and labor if I hire someone???

Thanks!

PS: Currently have an oil fired FHW with baseboards in the house and domestic hot water is directly off the oil-burner.

 

[free75degrees]

Wow, it seems like there is a new gasifier buyer every day on this board. Count me as one of them, although I am a little further along. I wonder if there was this much interest lastt year.

I was originally planning on going without storage initially, but changed my mind because I figured I could build my own storage with a much smaller incremental cost. Anyway, from scouring the posts on this site I learned that a tank will reduce the amount of wood you need to burn and make your life easier. If you are willing to put in the extra work and extra wood you can probably achieve the same oil savings without the storage. The problem is, if you are at work or alseep and your zones call for heat and there is no wood in the boiler, you will either have to get wood in the boiler, or burn oil. If you can manage to be there every time and add the wood then you will burn the same amount of oil as with a tank (hopefully zero). If you get a little lazy then you will probably burn more oil without the tank.

 

[MrEd]

In my case, I am home almost 100% of the time, so I can fire when needed (within reason). But of course during the summer, my understanding is that without the tank you couldn't really get DHW without using a tank. I just figure what percent of my oil useage is heat versus DHW. (Family of 6, lots of washing, lots of dishes, lots of showers).

I also love the idea of heating my hottub off of my Tarm.....and maybe even the pool early in the season...


free75degrees - care to share your plans for a homemade tank? any estimate on the cost versus a pre-built?

 

[free75degrees]

I have a description here:
https://www.hearth.com/econtent/index.php/forums/viewthread/17627/

I am closer to being done now and the total cost is around $1400, including the HX.

You mentioned heating a hot tub and pool, but don't forget your driveway and walkways!

 

[chuck172]

MrEd, I'll be following the posts here in your thread closely. I'm in the exact stage your in, except I just ordered the Solo 40. I'll be tankless this first winter for the reasons you mentioned. I'm also looking into bulding my own 800 gallon tank.
As I've been told the system will work reasonably well without storage. You may have to tend the boiler more often. By that I mean smaller and more frequent loads.
I'll pipe the Tarm in parallel with my oil boiler, Valving off for the future storage coils, and I have a super stor side arm for domestic hot water.

 

[Nofossil]

I ran my first year without a tank, and then added one for the second and third years. Didn't mak a big difference in wood consumption, but it does increase quality of life. Infinite hot water, the ability to skip days, more even house temperatures - all good.

 

[chrisfallis]

I ran a Tarm without storage and was sorry that I did. I tended to overload the firebox and idle the boiler quite a bit. This lead to excessive creosote and the inability to meet peak heat loads. I probably could have gotten a surplus propane tank or two in my basement to add heat storage. That would be cheaper than the collapsible tank that Tarm sells.

 

[NHFarmer]

Free 75 I also just put a deposit on a tarm solo40,I am planning to build my own storage.How are you planning to build your tank?

 

[free75degrees]

My tank is half buried in my basement slab. I used a sledge to make an 8'x6' hole in the slab then dug down about 3 feet deep. Then I poured a 4 inch slab at the bottom, then put 4 rows of 6inch deep cinder blocks for the walls. I took care when laying the cinder blocks to make sure that they were aligned so that I would be able to slide 2x4 pressure treated studs (with about 1/4' ripped off) down into the blocks. Then I put 32 5 foot PT studs down into the blocks (they go 3 blocks deep). This took some minor ripping on a table saw to make some they fit due to cinder block variation. These PT studs form the structure for the above grade walls. Inside of them I will use 3/4 plywood sheathing. Inside of the plywood/cinder blocks I will use 2 layers of 2" thick polyisocyanurate for an R value of 26. Above grade I will also add fiberglass batts in the stud wall to get a total of about R40 above grade. Inside of the polyiso I will use EPDM liner.

The total interior dimensions after insulation will be about 3'4" x 6' X 5'2", which will give me 800 gallons of water (less than the 1000 I originally wanted, the hole was a groan to dig).

For the lid I think I am going to build a stud frame with plywood and another 2 layers of the polyiso and attach this to the tank with hinges for easy opening. I need to give some thought to how I will make the seal. Right now I am leaning towards lining the bottom of the lid with more EPDM and taking care to ensure that it makes a nice even contact with the tank EPDM, which will be wrapped over the top of the stud frame.

I think I will also be adding some bracing across the top (below the lid) which will also give me a nice place to attach my coil HXs. It is kind of hard to picture, but one problem will be that the braces will need to pierce the EPDM above the water line. I am not happy about having to do this, but i think i might be able to get away with using metal pipe for the bracing, cut small hole for it to go through the EPDM, and where the EPDM has to stretch over the bracing I hope to be able to clamp the EPDM to the pipe with hose clamps to ensure a good seal. We'll see, i may have to experiment if it does not work...

 

[tyler drew]

New guy, very interesting posts. I to am in the market for a Tarm 40. The storage tank is a dilemma as it is to expensive. When I was talking to a rep from Tarm and explained that I couldn't afford a tank at this time, he recommended the Tarm 30 because it will call for heat more often. Does anyone have this model and do you find that it burns clean. Also, besides the size are there any drawbacks with this model because I don't see that anyone has it on this board?

 

[chuck172]

The tarm guy I spoke with told me if I was definitely going with storage in the future go with the Solo40. It will work out better. No tank, get the 30. For $600. more, consider the 40.
The size of your house and heat loss calculation will be a determining factor.

 

[tyler drew]

I'm confused about the storage tank. I have an indirect 40 gallon water heater now. I have never run out of hot water. My question is if I never run out with a 40 gallon tank why should I invest in a 800 gal. storage tank? Once the 800 gallons is hot and I only use 40 gallons won't the solo 40 be sitting idol building up creosote anyway? Could anyone give me the advantages of a storage tank.

 

[MrEd]

On a related note, I had planned on getting a Solo 60, and running without a tank first year and adding it down the road. The Tarm folks suggested that a Solo 60 was way to big, so I am reconsidering, but my house is about 3000sf, when not using the woodstove I burn 2000 gallons of oil per year (heat and hot water). Besides the house, I have a pool and hottub that I may consider piping into the system sooner or later and if I had capacity to space I might also heat a small greenhouse for 2 months per year to get a jump on my growing season.

My personality is always "bigger is better" (or buy the one you really need the first time) but what kind of problems might I run into down the road if I get a 60 and *don't* add all those extra zones? The cost difference between a 30/40 and a 60 is pretty minimal if you factor in how much it would cost to upgrade down the road.

 

[Nofossil]

Gasifiers need to run hot to run efficiently. Too cool, and it's just a conventional boiler. The ideal way to run them is flat out.

The problem with a boiler that's too large is that without storage, it can't run at full output for long (if at all). Therefore, it spends a lot of time idling and not gasifying. The only way to avoid this is to build a lot of small fires - not a great solution unless you like building fires.

A boiler that's well matched can run at or near full output with minimum idling. Storage allows you to run flat out for a while, then live off the stored heat until your next fire.