How Do You Connect Two Boilers?

What did you do for switching control to the back-up boiler if the coal boiler goes out?

Dott727 wrote:What did you do for switching control to the back-up boiler if the coal boiler goes out?

On mine I use a 3 pole 3 throw switch on the thermostat wires. It is manual operation only. If you would like to make yours an automatic changeover, we need to know how you will plumb it and what your propane unit is. The electrical wiring and controls are important as is the waters flow and control. Are there multiple zones?
I describe in an earlier post how to plumb them to run automatically without any wiring between them. When I was installing mine, the plumber that helped said that was the way he would do it. He didn't know anything about heating with coal but he knew plumbing.

A little advice. Hook it up so everything works automatically, you never know when the next two shovels full of coal are really just rocks because your neighbor spent hours hand painting and polishing them to get even with you because you are warm as toast for next to nothing and he's freezing his butt off paying through the nose!

coaledsweat wrote:

Dott727 wrote:What did you do for switching control to the back-up boiler if the coal boiler goes out?

On mine I use a 3 pole 3 throw switch on the thermostat wires. It is manual operation only. If you would like to make yours an automatic changeover, we need to know how you will plumb it and what your propane unit is. The electrical wiring and controls are important as is the waters flow and control. Are there multiple zones?
I describe in an earlier post how to plumb them to run automatically without any wiring between them. When I was installing mine, the plumber that helped said that was the way he would do it. He didn't know anything about heating with coal but he knew plumbing.

A little advice. Hook it up so everything works automatically, you never know when the next two shovels full of coal are really just rocks because your neighbor spent hours hand painting and polishing them to get even with you because you are warm as toast for next to nothing and he's freezing his butt off paying through the nose!

I had 5ton of coal delivered yesterday and temps are starting to fall, I really need to get this unit up and running. I to am working with a plumber that doesnt know about heating with coal. The reverse flow method recommended by AHS seams to be the easiest, but I am really looking for the best way, I only want to do this once.

I have a burnham propane boiler with two taco swithcing relays for zone control. In total I have 7 zones heat zones + an indirect fired water heater that is set as priority. When I spoke to Jeff at he also mentioned it may be necessary to createa dump zone.

Any advice would be greatly appreciated!

Thanks

Dwayne

Please get the model of the Burnham. Do you have one circulator pump or multiples?

The simple AHS plan may be the best. I'll see if I can find it on line.

Edit: That works. http://www.alternateheatingsystems.com/boilers_in_tandem.htm
Call AHS and ask what the control is with that combo. You may only have to fire the coal boiler to get it to take over, when it goes out it will revert back to propane. The two would be wired independently and the coal operated at 10*+ hotter temp more than likely.

coaledsweat wrote:Sufferin' succatash! I can't figure out how to load these things. They are scanned as photos. Should I rescan as something else? And how? This is starting to look like the computer that needs a hammer.

If you PM an E-mail I think I can attatch it. The file is to big I guess.

You most likely were saving them as BMP's at that file size. BMP doesn't compress. I converted the files you uploded into gif's, just to give you an idea each of your files were 20.3 MB's. The Gif's are 100KB's

or as grand total:

61,000 Kilobytes

compared to

300 Kilobytes

Huge difference.

There directions in the help forum for working with images. Not sure if noted there anywhere but when saving images such as screenshots or text use gif, for photo type images use .jpg .

coaledsweat wrote:Please get the model of the Burnham. Do you have one circulator pump or multiples?

The simple AHS plan may be the best. I'll see if I can find it on line.

Edit: That works. http://www.alternateheatingsystems.com/boilers_in_tandem.htm
Call AHS and ask what the control is with that combo. You may only have to fire the coal boiler to get it to take over, when it goes out it will revert back to propane. The two would be wired independently and the coal operated at 10*+ hotter temp more than likely.

It is a Burnham Model 206PVNI-02 and yes there are seperate pumps for each zone + one for the indirect water heater. These are controled with taco swithcing relays.

I believe your right with AHS setup. They use the coal boiler to heat the propane boiler with a reverse flow. The circulating pump between the units only runs when the coal boiler is at temp. The temperature on the propane boiler is set 10-20* cooler. If the coal goes out the propane takes over.

Thanks

Perfect, essentially what I described earlier. Now you're cooking!:onfire:

I want to do this with my current oil burner next spring/summer. Does each boiler need it's own chimney? From what I know you can only have one device per chimney but only one will be running at a time.

billw wrote:I want to do this with my current oil burner next spring/summer. Does each boiler need it's own chimney? From what I know you can only have one device per chimney but only one will be running at a time.

Only one appliance per chimney for solid fuel appliances per the national fire code, which usually is also adopted by state and local governments. It would be possible to have a combination fuel appliance that uses a single flue. The manufacturer of appliance would be responsible for certifying it's use. The fire code always applies, however, it allows for manufacturers to test and label products for use in ways you can not.

You can do what I do. Physically change the flue pipe seasonally. Summer oil burner boiler for heating hot water. Winter coal boiler. Only one is connected at a time. Auto switch over just takes a bit longer!

Thanks

Yanche,

Thanks for mentioning the manual switch over. That is what I was considering doing, thereby eliminating the oil burner for the winter. Makes me feel better knowing that someone with much more experience does that.

Sorry to reinvigorate an old thread, but it seems to fit my current situation well.

I bought a coal-o-matic back in the winter of 08/09 from Dave D and brought it home. Due to my being overseas for a year I didn't get it installed and now its in my basement and I am trying to plan its installation.

My situation is a follows. This boiler is for my house, a 1918ish appx 4000sf, with the plan that it will provide the majority of the heat. It is replacing a hand-fired Stelrad coal boiler rated for 120k and the Coal-o-Matic is 130k. The main boiler did have to occasionally help the Stelrad when we had sub zero weather.

The main boiler (gas) is a hot water gravity boiler. The system still works as a gravity system, and the Stelrad was operating as a gravity boiler as well. The down side was the Stelrad had been plumbed so it pushed hot water into one of the risers coming off the boiler - there are two (8" I think) risers that come off the main boiler. This left half of the house cool. The Stelrad sits right next to the main boiler.

The coal-o-matic is going to be on the other side of the basement in order to be able to get the coal direct from the bin (I used to haul ti across the basement in wheelbarrow).

The old system was more or less automatic with a low temp aquastat on the inbound pipe from the coal boiler which doesn't allow the main boiler to fire unless the water coming from the coal boiler went below the set level.

My current plan - is to hook up and wire up the coal-o-matic. Plumbing the two boilers together more or less the same as the Stelrad was. I am planning on adding a circulator between the two boilers. Based on my research on the heatinghelp site I think a Taco 010 will fit the bill. I'm looking at plumbing the two together with pex-al-pex. I know many don't like pex for these applications, but I think because I am so unsure of how this will end up that it is a relatively inexpensive opportunity for me to put it together and test it out.

OK - suggestions - advice etc???

Thanks Jay

I'm not positive but I believe the reason for not using Pex between boilers is for a run away boilers temp could overcome the physical properties of pex. Then again maybe I'm nuts.

Here's a question for you. If the way it was plumbed before led to a poorly balanced heat in the house why would you want to do this again with the new boiler? Why not go to a series setup where the return goes to the coal boiler, warm from coal to gas then gravity to radiation?

Or you could go with a parallel system with circ between the two boilers.

Mind you I'm just a peon here learning myself but these are the questions and suggestions that come to my unedjamakated mind

God bless you Jay and Thank-you for your service to our country. What ever I can do to help – you get it. My son is deploying again in Feb. Old threads are like potato salad – always around and the left overs are great . Plus it shows you know how to use the search.

stelradCoal wrote:Sorry to reinvigorate an old thread, but it seems to fit my current situation well.

I bought a coal-o-matic back in the winter of 08/09 from Dave D and brought it home. Due to my being overseas for a year I didn't get it installed and now its in my basement and I am trying to plan its installation.

My situation is a follows. This boiler is for my house, a 1918ish appx 4000sf, with the plan that it will provide the majority of the heat. It is replacing a hand-fired Stelrad coal boiler rated for 120k and the Coal-o-Matic is 130k. The main boiler did have to occasionally help the Stelrad when we had sub zero weather.

The main boiler (gas) is a hot water gravity boiler. The system still works as a gravity system, and the Stelrad was operating as a gravity boiler as well. The down side was the Stelrad had been plumbed so it pushed hot water into one of the risers coming off the boiler - there are two (8" I think) risers that come off the main boiler. This left half of the house cool. The Stelrad sits right next to the main boiler.

The coal-o-matic is going to be on the other side of the basement in order to be able to get the coal direct from the bin (I used to haul ti across the basement in wheelbarrow).

The old system was more or less automatic with a low temp aquastat on the inbound pipe from the coal boiler which doesn't allow the main boiler to fire unless the water coming from the coal boiler went below the set level.

First off – The simplest thing to do is to reverse the damage ( read that bad installation of the Seelrad) to your wonderful gravity flow hot water system. For all the world – finding a mechanic who knows even how to add to a system like yours much less ever build on again – well figure that IMPOSSIBLE!

So many modern pipe wrench draggers want to pump these systems and have no clue how to. A gravity flow system like yours will heat the house on a cool evening with just a small amount of energy flow out of the boiler – and it will heat your house on the coldest night as these systems can produce a great deal of flow when put to task. All you should upgrade is a modern (digital) outdoor reset temperature control for your boiler. More on this later if you want. Restore the system!

stelradCoal wrote:My current plan - is to hook up and wire up the coal-o-matic. Plumbing the two boilers together more or less the same as the Stelrad was. I am planning on adding a circulator between the two boilers. Based on my research on the heatinghelp site I think a Taco 010 will fit the bill. I'm looking at plumbing the two together with pex-al-pex. I know many don't like pex for these applications, but I think because I am so unsure of how this will end up that it is a relatively inexpensive opportunity for me to put it together and test it out.

OK - suggestions - advice etc???

Thanks Jay

Well maybe. You need to give us all a little better picture of what we have to work with. Hummm Pictures – yes that’s it – take lots of pictures so we can be voyeurs in your basement. No really. Spider webs – junk and all – all sides of the boiler – the debacle that is messing the flow of the system – everything.

At this point Ill suggest that you build a series system so the coal boiler heats the legacy boiler but we are going to have to be sure that we do it so as not to screw up the stratification of the gravity flow system. NOT EZ!!! But it can be done and it will provide you with a super comfortable house and a very reasonably economical system operation.

BUT—Let me get back to you on this when we have more info

Another thing you should do is read everything you can about gravity heating.

http://www.heatinghelp.com/search/results/gravity/1

Thanks for the thoughts guys. Sting, good luck and well wishes to your son - does he know if he is headed to IQ or AF? Tell him to stay safe either way!!

So - the gravity system. I agree with the comments completely in that the gravity system works and works WELL. I have no desire to change it at all. In fact that is sort of the root of my question:

How do I add in this Coal-o-Matic boiler without changing the overall characteristics of the Gravity system or making minimal changes?

Now, the Stelrad system was sort of kludged in there by piping the hot into the one riser rather than the main boiler, but it DID function pretty well as a gravity system.

My thinking on plumbing in the new coal-o-matic is I am going to need a pump between the two boilers. I had thought about gravity, but I think the distance and conditions make it relatively difficult and the cost of the piping would be quite a bit.

The idea of using PEX is cost and the fact that I want to be able to "test" the design out - I agree that it should probably be copper / black pipe for the permanent install.

Connecting the install to the old location is somewhat based on me being able to do that without draining the system. There are shutoffs close that I can use to isolate that section and do the install. If I try and connect to the main boiler body I believe I would have to drain it all and find/remove fittings from main boiler with associated danger of breakage etc...

In my mind I am thinking, plumb it to the Stelrad connection locations with a pump this year using pex. Use the system this year. If it performs as well as the Stelrad did then at the end of the season drain the system and connect the returning hot to the main boiler body, perhaps re-using the pex. Use the system the next heating season. If all works ok then re-plumb the pex with steel pipe.

If I put a pump in there will it block any residual gravity flow from the coal-o-matic?

Thoughts, plumbing ideas, anything?