question about non pressurized open type back boilers not common in usa

Catia · Apr 5, 2015

Been spending much time reading the archives, & doing searches.

It is AMAZING the things you find out you did not know.
Things your grandparents & their parents told you was right LOL
I have placed myself in the "I now know I didn't know jack ...." camp !!!

!

But I still am wondering why stoves with small "back boilers"
are not used in the USA more.

I'm seeing small wood stoves with these too. Not just big stoves.

Morso makes back boilers for their stoves--even for the Squirrel-- & they are available across the pond-but not in USA, Salamander (hobbit) does, & quite a few others.

Not talking about a full boiler system for a whole house, just some additional water heating a small radiator in another room, or enough for a short shower.

So here is/are my stupid question(s):

Why are they not sold here? Is it an issue of people just doing what they want to do & not properly plumbing-so the govt just said none of any kind?

I see there have been explosions in boiler systems & they're not pretty. I've seen a ton of stupid stuff people have done wrong, but surely there is a way to do it right???

I do understand trying to heat enough water to feed a whole house robs the heat & makes for creosote in a small wood stove in the chimney, but have also seen (limited) info on some small stoves feeding 1 radiator or a small storage tank without issues.

There are ways to do it where it is 'open' & not pressurized, & I am curious about it.

Obviously if a stove manufacturer makes these parts for their stoves, people are using them with success--

I'm one of those people who needs to know "why" ...Curiosity killed the cat...
...................................Satisfaction brought him back...

BrotherBart · Apr 5, 2015

For one thing if it is an option on the stove then it has to be operated during the EPA emissions testing. Don't know of any of the labs that have setups for that with water heating options.

HotCoals · Apr 5, 2015

Most of us have a hot water heater I guess.

The thought of heating a room ..maybe a small bath room that is a ways from the stove is a interesting thought though by using a radiator and a maybe a fan. Maybe a smaller radiator off a motorcycle. The unpressurized system would be fairly safe it seems.
Course you would need a pump and keep the system full of water.
Easier just to put a electric heater in there.

Auzzie Gumtree · Apr 5, 2015

We have the same thing in Australia we call them water jackets. They are mostly used to heat the water in your hot waster tank. Its a good idea as in summer you can use solar and in winter you can use the wood heater.

My nectre mega had 2 different water jackets. There is a small one 5 kW which is enough to do the domestic hot waster and then there is a 20 kW one which is enough to do approx 10 radiators.

The easiest way to set up is to gave a low pressure system which is very safe and uses the natural flow of hot water is as the waster heats it expands and therefore flows. Thrrmosyphen I think its called. If you use a pressure system then you would have to use a heat exchanger still a simple process.

When I was designing my house, which unfortunately never eventuated I incorporated wood stove with radiators.

HotCoals · Apr 5, 2015

Auzzie Gumtree said:
We have the same thing in Australia we call them water jackets. They are mostly used to heat the water in your hot waster tank. Its a good idea as in summer you can use solar and in winter you can use the wood heater.

My nectre mega had 2 different water jackets. There is a small one 5 kW which is enough to do the domestic hot waster and then there is a 20 kW one which is enough to do approx 10 radiators.

The easiest way to set up is to gave a low pressure system which is very safe and uses the natural flow of hot water is as the waster heats it expands and therefore flows. Thrrmosyphen I think its called. If you use a pressure system then you would have to use a heat exchanger still a simple process.

When I was designing my house, which unfortunately never eventuated I incorporated wood stove with radiators.

That is interesting..no pump needed eh?

Oldman47 · Apr 5, 2015

Even huge furnaces used to produce power are often run with no pump to circulate the water. They use tubing run in a vertical path in the boiler to promote upward flow and then let the cooler water in the drum circulate back down the outside where it doesn't get heated until it again reaches the bottom and starts rising. With colder feedwater coming into the drum constantly and steam constantly coming off the drum you get very strong natural circulation. It is often done on what power plant people consider lower pressure systems, under 2400 PSI. High pressure systems, over 3500 PSI, no longer produce any steam so natural circulation does not work on them. (Above 3206 PSIG steam no longer can exist.)

Squirrel · Apr 5, 2015

I'd be happy if I could just install a tempering tank close to my stove and feeding my hot water heater. That way I wouldn't be heating water from the well directly with electricity.
I just can't find a suitable un-insulated holding tank with top and bottom connections.

begreen · Apr 5, 2015

It's not a simple question. There are trade-offs when scavenging heat from the stove. This can be done as a retrofit, but be prepared for some experimentation.
Here's a primer: http://www.gulland.ca/homenergy/stove.htm

Catia · Apr 5, 2015

yes, thermosyphon-i think that's what it's called--that's what the one I viewed that used a salamander hobbit was set up for.

It was in a cabin/hut/tiny home--it heated a radiator--a regular cast iron radiator.
here is a link to the you tube video

Note: the temps given are in Celsius.
Not saying the set up is pretty, not for a regular home, but a lot of neat things can be done with copper tubing...

Just to be clear--I am not talking about retrofitting a home-made type of job-Salamander makes them specifically for their stoves & so does Morso, many other stove brand make them too.

I'm also not questioning that the EPA didn't test stoves with these devices attached--the back boilers aren't available on the USA models.

(Though I do believe there is a wood cook stove that is available with that type of set up, but on a grander scale--one of those $7k wood burning cook stoves, can't remember the brand. But I believe true wood burning cook stoves might not be a part of the EPA regulatory stuff, I believe there is a line drawn somewhere between cooking & heating for wood stoves.)

I'm just trying to learn about it. It does seem there is some issue with corrosion & water deposit stuff, but the open system looks pretty safe.

Some people who have small wood stoves on boats use the little boilers too.

Catia · Apr 5, 2015

Squirrel--they have small HW tanks that are RV sized--there are other types of holding tanks too--what size are you thinking of?
My thought is a used one might be had on the cheap from someone parting out an RV.

Squirrel · Apr 6, 2015

I was thinking a 10-20 gal vertical tank with top and bottom connections sitting near the stove overnight would warm enough water overnight to replace the hot water used in the morning, rather than replacing that water in the heater with 10* well water.
The tank needs to be good for 100psi and potable water. It also needs to look reasonable as it will be visible. I will be contacting a local stainless steel shop to see if they can make me something for a reasonable price as I can't find anything available. I think SS would be good because I anticipate it getting lots of condensation on the outside.

edyit · Apr 6, 2015

I had an old hot water tank that the elements were going in so i set that up as a prewarming tank before the new hot water tank. water goes into that tank, gets to about room temperature then goes into the hot water tank to be heated. if you can solder its a pretty easy and quick job.

kennyp2339 · Apr 6, 2015

I've seen homemade ones on that buying Alaska tv show, I saw one retrofitted to a blaze king princess and another on a Kodiak. It was very clearly a homemade setup. I would like to do something like to my stove, I would put a radiator upstairs in the living room to help take the edge off of the cold.

Catia · Apr 6, 2015

Squirrel--Trying to figure out what kind of tank you are looking for--you can always built something around it or make it decorative ...or just go 'industrial'.
any of these similar to what you're thinking? The 3rd link is to a solar water tank & pretty neat, I know nothing about them, but now want to learn.

Do you have any pics of what you're looking for?

http://www.walmart.com/ip/Wayne-Wat...fault&beacon_version=1.0.1&findingMethod=p13n

http://www.westmarine.com/buy/west-...gallon-front-rear-mounts--13915103/zoomImages

http://www.ebay.com/itm/Solar-Hot-W...304-Stainless-low-pressure-only-/361179447602

begreen · Apr 7, 2015

kennyp2339 said:
I've seen homemade ones on that buying Alaska tv show, I saw one retrofitted to a blaze king princess and another on a Kodiak. It was very clearly a homemade setup. I would like to do something like to my stove, I would put a radiator upstairs in the living room to help take the edge off of the cold.

Did you read up in the Gulland primer posted earlier?

Catia · Apr 7, 2015

Here's another question:
I've read some about adding thermal mass around the stove & hearth area to retain heat.

Where does the line get drawn between adding thermal mass around the stove & robbing heat from the stove that creates unclean burning?

I haven't finished my morning coffee...

DanCorcoran · Apr 7, 2015

Squirrel said:
I was thinking a 10-20 gal vertical tank with top and bottom connections sitting near the stove overnight would warm enough water overnight to replace the hot water used in the morning, rather than replacing that water in the heater with 10* well water.
The tank needs to be good for 100psi and potable water. It also needs to look reasonable as it will be visible. I will be contacting a local stainless steel shop to see if they can make me something for a reasonable price as I can't find anything available. I think SS would be good because I anticipate it getting lots of condensation on the outside.

But as soon as you fed that warm water to the hot water heater, wouldn't you be bringing 10-degree well water into your stove room? I guess as long as your wood stove is oversized enough, it wouldn't matter. On really cold nights, my wood stove struggles to keep temps up, so adding 10-degree water to the mix would be a negative.

Catia · Apr 8, 2015

I've read the article, that's a nice set up, but it still doesn't answer my questions about small stoves with back boilers that are made by the manufacturer of those small stoves, or the thermosyphon type of set up.

Also am still wondering about the point where a difference occurs between adding thermal mass, & the point where it begins robbing heat & creating inefficient/dirty burns.

I believe the back boilers on the European small wood stoves are attached to the rear/back & not inside of the firebox.
It also appears the amount of water heated is much smaller than what you'd need to supply all of your HW, just feeding 1 radiator.

begreen · Apr 8, 2015

Note that in the article posted earlier the guru of wood burning John Gulland found the back tank attached to his PE worked the best.

BKVP · Apr 9, 2015

BrotherBart said:
For one thing if it is an option on the stove then it has to be operated during the EPA emissions testing. Don't know of any of the labs that have setups for that with water heating options.

It has to also be operated in the SAFETY TEST!

BKVP · Apr 9, 2015

As many of you know, I was in New Zealand about a month ago. I visited many retailers of wood stoves and also a test lab. I also visited with a distributor in Christchurch.

I was told our stoves would have to be fitted and tested for a "wetback". I was not certain what they meant until I visited the test agencies. After seeing the systems offered by about 3 different stove companies in NZ, I inquired of a few retailers the most important question to a manufacturer..."what is the demand"?

So first I was told that in order to get floor space you should have your stoves tested for use with a wetback system. Then I inquired as to actual sales. "What percentage of wood stoves tested and approved to be used with a wetback are actually sold or installed with such a system?" Retailer after retailer said less than 10%.

I think you get the idea.

Squirrel · Apr 9, 2015

50 years ago we moved into a brand new house that had a back boiler built into a coal burning fireplace, needless to say it heated neither room nor water and was soon removed. I grew up in the UK and at that time back boilers of various kinds killed or maimed a lot of people.
My plan is to design a "tank" that will hold enough water for a couple of showers, place it near my stove so it picks up radiant heat. This warmed water will then feed the inlet to my hot water tank which is two feet away from the stove but in a separate room. Yes this may mean burning a little extra wood (but so does making my coffee and toast I guess).
Introducing cold water into the stove room, which happens to be the kitchen, may cool it a bit but this will also happen in our hot humid summers so what you lose on the roundabouts you gain on the swings. Hopefully it will work as a small air conditioner/dehumidifier too. I know I'll need a tray under it to catch condensation in the summer but am still working on the best shape and size which can be built easily.

begreen · Apr 9, 2015

BKVP said:
As many of you know, I was in New Zealand about a month ago. I visited many retailers of wood stoves and also a test lab. I also visited with a distributor in Christchurch.

I was told our stoves would have to be fitted and tested for a "wetback". I was not certain what they meant until I visited the test agencies. After seeing the systems offered by about 3 different stove companies in NZ, I inquired of a few retailers the most important question to a manufacturer..."what is the demand"?

So first I was told that in order to get floor space you should have your stoves tested for use with a wetback system. Then I inquired as to actual sales. "What percentage of wood stoves tested and approved to be used with a wetback are actually sold or installed with such a system?" Retailer after retailer said less than 10%.

I think you get the idea.

Yes, it's like folks demanding to have a stove that can be run open with a door screen like a fireplace. That gets tried once and then the screen gathers dust.

question about non pressurized open type back boilers not common in usa

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