HS Tarm Wood Boiler w/Heat Storage

[SkogenMe]

You can store the heat and fire the boiler up once a week in the summertime and get all the hot water you need.
Almost sounds too good to be true. You know the old saying, it probably is.
I'm close to buying it though.

I have heated our house for 15 years with a Dumont unit (Boiler + 1,500 gal storage). It is great...house @68 deg on programmable thermostats, fire for 4 hrs/day in January.

Just a note tho' ..part of the too good to be true is if you use it for hot water heat in the summer, your basement is going to be some warm even with an insulated tank. We did that for three years..ended up putting in an electric hot water heater that we used in the summer...then replaced that with a solar system/gas boiler in series. We use the solar in the summer, gas/solar in the winter. We stopped using the hot water coil in the winter because the piping got a little complicated and it isn't "free"...it has a noticable draw on the storage tank temperature.

0.02 worth

 

[charlz]

We did that for three years..ended up putting in an electric hot water heater that we used in the summer...then replaced that with a solar system/gas boiler in series. We use the solar in the summer, gas/solar in the winter.

I am curious as to what type of solar system you put in? Any estimate as to cost savings?

 

[schmism]

You can store the heat and fire the boiler up once a week in the summertime and get all the hot water you need.

i want to know what kind of space aged nasa tank they have that will keep water at 120deg for a week with no additional energy input.

on that point i have to call BS! my guess you could effectively store heated water for 2 days tops.

 

[chuck172]

schmism, I'm with you. It just doesn't seem possible. Here is a direct quote from the Tarm Literature:
"On most days in the winter, you will be able to load the boiler once in 24 hours. In summer you will be able to go 4-10 days between firings to heat all your domestic hot water. "
The tanks are not something out of sci-fi either, look like junk but very expensive.

 

[SkogenMe]

I am curious as to what type of solar system you put in? Any estimate as to cost savings?

Evacuated tube/glycol/120 gal water tank....cost savings wasn't really the goal. It got us out of the electric hot water heating business.

 

[SkogenMe]

i want to know what kind of space aged nasa tank they have that will keep water at 120deg for a week with no additional energy input.

on that point i have to call BS! my guess you could effectively store heated water for 2 days tops.

No need for NASA to get involved.....start with an insulated tank that is at 190 deg..seven days later you will have a tank that is 120 deg (your mileage may vary). Remember we are not talking about your basic residential hot water tank here, we are talking about 1,200 gals of water that in the winter has to be between 190 and 140 deg in order to be effective for baseboard heat.

It does bring up another issue with domestic hot water heating in the summer...because it is hard to get motived to have a fire on summer days you probably would stretch it out to a week. Even with a tempering valve you see a fairly wide difference in shower hot water temperatures from start of the week to the end of the week.

 

[charlz]

Evacuated tube/glycol/120 gal water tank....cost savings wasn't really the goal. It got us out of the electric hot water heating business.

Not to hijack the thread but.... Being that my hot water is all electric is where the cost savings question came from. So the solar can provide 100% of your hot water needs in summer? How many people in your household and does it maintain temp overnight pretty well? for morning showers etc.?

Thanks!
Charles

 

[Sigarms]

No need for NASA to get involved.....start with an insulated tank that is at 190 deg..seven days later you will have a tank that is 120 deg (your mileage may vary). Remember we are not talking about your basic residential hot water tank here, we are talking about 1,200 gals of water that in the winter has to be between 190 and 140 deg in order to be effective for baseboard heat.

Actually, I know of one German manufacturer of residential hot water storage tanks that at 190 degrees, seven days later you'll be at 145 degrees.

 

[SkogenMe]

Not to hijack the thread but.... Being that my hot water is all electric is where the cost savings question came from. So the solar can provide 100% of your hot water needs in summer? How many people in your household and does it maintain temp overnight pretty well? for morning showers etc.?

Thanks!
Charles

Sorry I haven't kept track of it acurately but yes it provides 99.9% of summer hot water needs April - September. Family of four...As the two kids move into their teenage years we do exceed capacity occasionally. We don't plan usage very closely so if you get in the situation of: extra sleep over friends, a weeks load of teenage laundry, lots of dishes all between sundown and sunup...we just flip on the gas. We have only gotten one propane delivery in four years so the cost of turning on the gas isn't very closely connected to using it! With a little more planning you could use less/or no gas.

After about three days without sun we start to notice low hot water temps, so storing overnight is not a problem. Several people have noted that the tank is bigger than it needs to be, but on that third day it is nice to have started with somewhere around 120 gals of water that is about 140 deg.

Maybe bringing the thread back a little...the gas unit we have is a two loop one which has separate heating loops for domestic hot water and baseboard heat. I don't know anything about the Tarm unit, but the Dumont I have was set up as a dual fuel unit (wood/oil). We burned oil for the first month we installed it, switched to wood and never fired it again with oil. There is so much ash around the burner gun whenever I clean the furnace, I can't imagine that it would have been too successful a setup. We went 12 years without a backup heat source (not good!). Now with the gas it is very easy to cut the wood furnace out and put the gas on-line.

 

[Luremaker]

Here is something I am considering making to offset summer hot water heating. A simple batch hot water collector. Looks simple and requires no serious plumbing. It should work fine for 6-7 months / year around here.

Solar Hot Water Batch Collector - DIY Solar Shower - Homemade Hot Water Heater - Tankless Water Heaters — ByExample.com