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Get Powered Up! Certified Energy Manager Jeff Yago answers your alternative energy questions

Wondering about a great new energy-saving device
you found on the Internet? Then CLICK HERE!

Sorry. Jeff no longer answers questions online.
This will remain as a searchable
resource for all BHM website visitors.

Archive for the ‘Hydronic’ Category


Vendors for fireplace hydronic water jackets?

Tuesday, June 23rd, 2009


“There are hot water coils designed to fit inside traditional free-standing woodstoves, and hydronic water jackets designed to fit inside a conventional masonry fireplace”

This is exciting to me.

The references at the bottom seem to be selling complete outdoor furnaces, not the simple heat exchanger in the photo on the article Web page. Do you have the name(s) of a vendor or two that make these water jackets for conventional masonry fireplaces?

With Appreciation,



I have answered this question before.

Stricter Federal government regulations and easy lawsuits against manufacturers have driven all the manufacturers of this type equipment out of the US market.

Back in the 70’s and 80’s there were many manufacturers of wood-fired hot water heaters, hydronic fireplaces, and hot water coil inserts for wood stoves.  Some moved to Mexico and are selling lots of these products in Mexico and others just went out of business.

There may be one or two left, but about the only water heating wood stoves made now are the outdoor wood-fired boilers you see advertised in this magazine that pipe the hot water into the house.

Hope this helps,

Jeff Yago


Hydronic woodstove

Wednesday, December 31st, 2008

Hi Jeff,

I have a fireplace in my basement and wood like to augment my propane/hydronic heating system with a wood stove fireplace insert similar to your setup. My question is about the water jacket that you use. Is it off the shelf product? Custom? Can you provide insight into the set-up that you did not detail. Your expertise would be appreciated!

Thom Pecoraro
Stephentown, NY


This is another great example of class action lawsuits forcing great products off the market.

Throughout the 1970’s energy crisis there were several nationally sold fireplace inserts and fireplace grates that heated water. This made it easy to pipe all the wood heat to hydronic baseboard heaters in other parts of the house, or to a hot water coil in the ductwork and heat the return air being ducted to the other rooms without operating the electric strip heaters or gas burners. I purchased several of these “Hydro-Heaters” for other projects, including the one I now have in our solar home. I had it the new unit boxed up and put in storage for almost 15 years, then installed it in 1992, and it has worked perfectly for the past 16 years.

There also was a firm in northern California I visited in the late 1990’s that was making a great wood-fired hot water heater for remote home-sites. It looked like a standard gas hot water heater, but the bottom half was a fire-box and the flue went up the center. You built a small wood fire and waited about 30 minutes, then you had enough hot water for several showers and dish-washing. They made a “tank-less” version that was just a fire-box surrounded by a water jacket, and you pumped the heated water to a larger storage tank or hot tub. I also purchased one of each and am still keeping them for future since this firm is now out of business and to my knowledge was the last company still making these in the US.

What happened was most state and federal agencies viewed these products the same as a steam boiler since they can explode if not properly installed. For example, all of the models that were sold in the 1970’s always came with a temperature relief valve and a pressure relief valve. If you have a large fire going and the water pump stopped pumping when the power went out, without any water flow the water jacket would quickly turn all water still left in the heater to steam. I have witnessed several times when this happened and all the only thing you saw was some some steam safely venting to a floor drain or outside. However, if the relief valves were not properly installed, the pressure could reach a level that would rupture the steel jacket or under extreme cases even explode. There were not only cases of tank ruptures due to missing relief valves, but even a few cases where a relief valve was piped to the outside and a small drip through the valve due to a weak spring would run down the pipe and freeze during winter weather. After several days the relief valve’s discharge pipe would totally plug up with ice, then if the pressure increased due to a power outage stopping the pump there was no place for the pressure to vent.

I know that there are millions of these wood fired hot water heaters and hydronic fireplace grates being sold in third world countries every year, and I think the California manufacturer moved his operation to Mexico years ago, but I am not aware of anyone making a hydronic fireplace insert that is legal today. If any reader out there can provide this information we all would be grateful, but I think the cost to get these UL listed and the cost for liability insurance for any manufacturer makes this impossible today.

If you really want to heat your home with wood using a hydronic system, I suggest installing one of the many outdoor packaged units you see advertised in Backwoods Home, and in an article I provided on this subject. Since these outdoor units use a non-pressurized water jacket system to pipe hot water to heat the home, they are safe and easy to install.

Good Luck!

Jeff Yago


Old hot water heating system

Sunday, September 14th, 2008

Dear Jeff,

I have a 4,000 sq ft Victorian home that built around 1900. I purchased it 2 years ago. It came with aluminum siding and a new roof with a ridge vent. I soon learned that it had no insulation in the attic or walls so contracted blow-in insulation and soffit and proper vents to make the ridge vent function properly. We also replaced 11 of the 43 windows and tightened up most of the drafts. However, my oil bill is still about $3,000 per heating season. I was going to update the hydronic hot water generator after last season but the oil company stuck me with a full tank in April. So here I am spending another 3K on oil.

My dilemma is this, the hot water system consists of a 4 inch supply header (around 60 feet long) with individual feeds to each radiator that go back through another 4 inch return header. I’m sure this is great for getting the same temperature water to all of the radiators but I’m concerned that the modern generators aren’t suited to Header type systems. I have a summer cottage at the shore that has a modern Weil McClain generator and noticed that there is no such header. It works great making all of the radiators quite hot and heats the house very quickly. If I go to a modern High Efficiency gas system, will I have to change the whole piping arrangement ?

I should also point out that I invested about $600 on piping insulation and insulated both supply and return headers as well as the accessible portions of the branches to the radiators in the basement and crawl spaces. I figure most of the energy I’m wasting is heating up this large volume of water in both the generator (probably built in the 40’s -General motors, Delco heat) and headers.

Thanks for your help.


Larry W.

Haddonfield, NJ


Sounds like you have a real problem.

You first need to decide if you want to stick with oil or switch to gas. I assume your existing oil boiler is very old and past time to replace. Many boilers designed for gas firing can be converted to oil or even use both, but if it is over 20 years old it is time to replace. Your piping headers and piping distribution layout is a function of the heating system design, not the boiler.

You did not say if your system has a pump, but most systems using large headers in residential systems are designed to operate without any pumping, so most likely this is a very old system which did not use pumps. If the radiators are OK, I would scrap the boiler, headers, and replace with new high efficiency boiler, zone valves, and circulating pump. With a pump your piping will be in the 1″ TO 1-1/2″ size range at the boiler, and most likely 1/2 to 3/4″ run-outs from the mains to the radiation. With a pump system, you can have several zone valves and wall thermostats to allow having different temperatures in different rooms to save energy. Finally, decide if oil or gas in your area will be your best long term best choice and go with that fuel type boiler.

Good luck,

Jeff Yago


Thanks for your input. Here are some more specifics about my system that should clarify things:

Yes, there is a large circulator pump on the return side of the boiler. It apparently forces hot water out and into the main supply header. The supply header runs the length of the house 4 inch most of the way and then 3 inch for the last 15 feet. Then 1 ” and 1 1/2″ branches go to each individual radiator. I have to say, this seems like a good system to evenly distribute the hot water to all of the radiators. And I have to ask, without a header, how is this accomplished ? Do modern systems run like a daisy chain, with each successive radiator downstream from the next ? Doesn’t that make the radiators early in the chain too hot and those at the end too cold ? What I was hoping to hear from you is to be able to just replace my boiler with a new Modern (I have gas service in my house now) gas high efficiency boiler and still use the header system for distribution. Especially since the piping is now freshly insulated. I also can’t replace the run-outs to the radiators with smaller piping because those pipes are mostly buried in the walls. Thanks again for your help.



I was trying to say that most of today’s systems do not require large header piping which saves pipe and insulation costs. For most residential hydronic heating systems, a 1-1/2 to 2″ main piping header is more than large enough to handle any water flow a typical residential circulating pump can handle. You will never see a 4″ main header pipe today unless the facility is a school or large office with much larger boilers and circulating pumps.

I still bet this system was originally designed to operate by gravity flow (heat rises, cold falls) without a pump. Many of these older systems worked this way by using over-sized piping. If this piping is in good condition, the only real problem is the higher heat losses due to the larger pipe surface area and related higher pipe insulation costs. If this piping is in good condition, you can use almost any size pump and boiler without any heat distribution problem. However, if it is old, you better hope you never have a leak as this old piping is almost impossible to repair due to thinning pipe walls or corrosion. Once you try to un-screw a fitting something else will break or leak and it never ends.

Good Luck,

Jeff Yago


Gravity hydronic heat

Wednesday, August 13th, 2008


I have a home in upstate NY that and I am concerned that its water system may freeze during power outages. I am thinking about a gravity hydronic system using the existing gas water heater and a couple of HW heat baseboard units all connected in a gravity system. Do you think that this is a viable solution? If so, could you point me to some resources that I could use?


Tom Hodge


Although it is possible to design a heating system that does not require any pumps or electric devices to operate, there are many technical reasons why this will not do what you think it will.

First, older gravity flow hydronic heating systems worked because their piping was large and routed to promote proper flow. Second, they used a very hot 180 degree water temperature to create the large temperature difference required to create the flow. A typical glass-lined residential water heater is usually heated to only 125 to 130 degrees which will not have much temperature difference to produce the flow, and most hot water tanks are not designed to operate at 180 degrees without damage to the glass lining.

Another issue is normal flow direction. Since you would be connecting the supply pipe from the discharge side of hot water tank up to the heating appliance and the return pipe back to the inlet side of the hot water tank, this is a dead short across the tank. This means when you open a faucet somewhere in the house, the water can flow “backwards” from the cold line into the hot line by passing through the appliance.

Why not install an externally vented gas wall heater that uses a non-electric igniter? You could locate in an central area.

Good luck,

Jeff Yago


Emergency heat

Monday, July 28th, 2008


If you were going to buy a stove to put in your basement for heat (and cooking) in the event of a blizzard or national emergency what would you buy for your home?


Fort Pierre, SD


Great question. I have designed several totally off grid homes in the extreme north including northern Idaho and believe me, that’s rural! We designed propane fired hot water boiler systems for all of these. These boilers are very efficient, are smaller than a 2-drawer file cabinet, and are self-contained with all controls. They also only require a very small fractional HP circulating pump to move the heating hot water through all the baseboard radiators in each room. We also have used the same type boilers with radiant floor heat which is really efficient. You will however, need a small backup power inverter or small generator to power the pump and temperature controls.

If this is not what you want, there are some great non-electric wood stoves, and provide both space heat and a cook top. Some can connected to your existing ducted air system and some are hydronic and can be piped into your baseboard hot water heating system, but this would require electric power to operate any pumps or fans. Our solar home has a central hydronic wood stove that can heat the entire home if I don’t want to run the propane hot water boiler, and we have a separate wood cook stove in the kitchen/dining area that we use on cold winter days that really puts out the heat with very little firewood. It looks like it was made in 1860, but actually there are now several manufacturers making new stoves that look like the old wood stove of the turn of the century.

I advise clients to install an in ground propane tank that is 500 to 1000 gallons in size, as this gives you months of space heating, domestic hot water, and cooking if the power goes out and the weather is too bad to re-fill a smaller tank. The short answer is, you need 2 stoves – a propane boiler or cook stove and a wood stove for heating and/or cooking.

Good Luck and let us know how this works out for you,

Jeff Yago


Hydronic wood stove

Thursday, July 10th, 2008

Some 30 years ago I help install an hydronic system in a house in northeast Texas that used a similar system but went a lot farther: We ran hi-temp PVC thru the slab and out into a coil (radiator) in a 10,000 gallon water tank. Then we hooked it up with black pipe to the fireplace by embedding it into the hi-temp (stove) cement. Added a pop off valve at a low pressure (approx 110 psi) and a pump for backup.

This allowed the water to be heated from the fireplace and due to the temperature difference it move the water thru the system (slab and water tank) by itself. The water heated the slab and the water tank. Once the water was heated your house stayed warm and you had hot water for your home.

Come spring time you turn off the stove and switch the water coil in the 10,000 gallon tank to the sun concentrator to heat the water for the house.

All of this is not hard, just a lot of money!

Kevin Bradway


As I mentioned in the article, we designed several systems that used a storage tank. Tank water was heated from the hydronic wood stove which was then circulated later at night to circulate to the home’s floor slab after the fire was out. Most of these tanks were under 1000 gallons since they would be located in the garage, and they took about 4 hours of a really big fire to heat up. If you had a 10,000 gallon tank, it must have taken days to get the water hot, but then you would be able to heat for days without a fire once it was!

We used standard 3/4″ copper which come in 60 foot rolls for our heat exchanger and placed two coils in the tank which kept the water that circulated through the stove and coils from mixing with the water that stayed in the tank. All of our systems required two pumps and three automatic zone valves to re-direct the flows since you need three separate operating modes: stove to tank, stove to house, and tank to house. If you were able to do all this without any pumps or valves, you must have had a really good thermo-syphen effect with your hydronic stove.

Thanks for the description of your very large system.

Jeff Yago



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