Boiler help

[kravvelocity]

Hello All,

This is my first time burning with wood. I bought a house that has an oil boiler and a wood boiler. The wood boiler is an itisca wb410 which i cant find any info on or manuals. I would like to use the wood boiler as a primary and oil as backup. I tested out the boiler last night and was working good. I have 2 circulator pumps. off the wood boiler is HS-105-SM-R3 bell and gossett. The pump on the oil boiler is a taco i believe.

All the valves are labeled what you turn on and shut off to run the wood boiler. This all works fine but my only concern is when all the thermostats are off there is no loop. The only time a loop is open is when on of the zones calls for heat. Is this ok or do I need to do something different.

I can upload pictures if anyone need to see whats going on.

Thanks for any info or advise!!

Travis

 

[maple1]

There is more than one way to tie boilers together & to the system. Yes, pics likely needed. Of everything. Seems there should be some kind of loop between boilers. Unless it was plumbed so as to need manual intervention with valve turning, when you want to switch fuels. Which isn't a right thing to do but that doesn't matter to some sometimes...

 

[peakbagger]

It is definitely worth spending the time tracing out the lines and figured out what the controls will do.

There should be be two possible three over temperature safeties. There should be a high temperature switch that removes power from air damper motor so that it closes. There should be a second switch that causes a dump valve to open which is plumbed to either a dedicated radiator or a heating zone. There should be no isolation valves on the dump zone. There also should be a safety relief valve and it may be plumbed into the firebox to spray water at the fire to put it out if all else fails. Whatever you do never run it with the doors open of the air damper forced open.

Many older installs are home brew to no known code and are dependent on the operator to hope he knows how to run it. It can be made safe but may require some additional piping.

 

[kravvelocity]

Both loops are tied together. I can run wood as main with oil as backup, wood alone or oil alone. I took some pics and tried to label them to show the direction. the green pump on the oil boiler is shut off and water is cut off to it

red is hot from the wood boiler and blue is cold return back. 1-5 are the zones with thermostats.

 

[kravvelocity]

It is definitely worth spending the time tracing out the lines and figured out what the controls will do.

There should be be two possible three over temperature safeties. There should be a high temperature switch that removes power from air damper motor so that it closes. There should be a second switch that causes a dump valve to open which is plumbed to either a dedicated radiator or a heating zone. There should be no isolation valves on the dump zone. There also should be a safety relief valve and it may be plumbed into the firebox to spray water at the fire to put it out if all else fails. Whatever you do never run it with the doors open of the air damper forced open.

Many older installs are home brew to no known code and are dependent on the operator to hope he knows how to run it. It can be made safe but may require some additional piping.

I made sure the electronic damper was working and it does. once it hits 180 it shuts the damper. I am trying to run this as safe as possible. I am deff not trying to burn down or house. I had some one with a boiler come lite this for the first time so he could watch and see if there was any problems. he went over to make sure it was working correctly. The only thing i dont see is a dump zone. That was one thing the guy who looked it said it was missing. There is a pressure relief valve on both boilers.

 

[peakbagger]

I have similar vintage wood boiler that was used and came out of house where it was plumbed roughly the same. I initially installed mine similarly with a dump zone since it had one after researching the manuals from several similar vintage brands of wood boilers. Some had dump valves some didn't. Somewhat like driving an antique car, when the car was new it may have met the safety standards in effect at the time but compared to current vehicles, the antique does not meet the current safety standards and would be considered unsafe compared to other new vehicles on the market.

The trade off with the early designs is they were not particularly efficient and potentially major creosote producers. Unless you want to sit in front of the boiler and feed it sticks of wood to match the heating demand of the house, at some point when there I no call for heat, the air damper will close. At this point you now have a hot boiler that has been starved for air. Without air the wood keeps turning to gas but it does not burn completely. These unburnt gases go up the stack and many of them cool off in the stack and condense out on the walls of the stack forming creosote. My neighbor had a similar set up and ended up permanently installing an extension ladder on his chimney as he had to clean it frequently. He had several chimney fires even though he was cleaning it monthly. He also burned relatively green wood which made things worse. Eventually he cracked his tiles and melted a liner. His experience is worst case as he tended to fill up in the morning to get the house warm and then cram it full of wood when he left. Once the zones shut down the damper would shut and it would smoulder for hours. I on the other had only ran my boiler when I was home awith seasoned wood and had time to babysit the boiler and there was plenty of heating demand. There is no one home during the day and I would travel frequently with the thermostat turned down. When I got home I would fire the wood boiler and use it to get the house up to temperature. Once the house started warming up I would back off on feeding the boiler wood and hopefully time it so the boiler was out before the heating demand stopped so the air damper would shut. Rarely did I run it in shoulder seasons as it wasn't worth starting it up and babysittng it. I ended up adding 500 gallons of storage and my wood usage went up to the point where I haven't bought oil for several years. I redid the controls and the piping so its somewhat automated although I still need to keep an eye out to reduce wood to the boiler when the storage temp is being maxed out.

I expect you could add a dump zone to the system. All it would require is putting a bypass around one of the zone valves and putting a new zone valve in the bypass. In the older designs like mine, the zone valve is controlled by a temperature switch installed in the water jacket of the boiler. The switch is set a few degrees higher than the air damper switch. Frequently there are spare plugs on the water jacket you can use to install a temperature switch. On the older units like mine, the zone valve is normally closed and the thermal switch closes when the boiler temp gets too high which feeds power to the dump zone valve and it opens. The problem is if the power to the boiler turns off due to a power outage or someone trips the breaker, the dump valve will not work even if the air damper closes. The current method is install a valve that is spring loaded so it is normally open, the new temperature switch on the boiler will be wired normally closed when the temp is below setpoint, this closes the dump zone valve and the heating system works normally. When the temperature goes over the setpoint the switch opens and the zone valve opens as there is no power sent to it. If the power goes out, the dump zone valve also opens. A major side benefit is that many wood boilers can still be run at a low wood feed rate using natural circulation even though the power is off and the pump is not running. Its very dependent on the piping. I think your style zone valves have a lever on the bottom that you can use to manually open them during a power outage and you may be able to heat the house somewhat without power even if you are not there as at least one zone will have heat. Its definitely not guaranteed but might get you out of pinch.

 

[maple1]

What exactly do you mean by 'there is no loop'? There should always be a loop, to somewhere. But not always to your zones/loads, no, if no call for heat.

If you are meaning rather a way to dump heat from the wood boiler - above post covers the basics. That requires a normally open zone valve, a controller for it, and a load preferably right above the wood boiler. If you can't plumb to one of your zones for that to use it for a load (my system uses my two second floor zones for that), you could add in another load just for that. (Pics don't give a good idea where the wood boiler is with respect to the oil & zones & rest of system). Say, maybe a big cast iron rad on the floor right above it. Should be right above to allow good convective flow. Because a proper dump zone will also be able to dump heat when the power goes out - which is also why you use a normally open zone valve for it, in between the boiler & the dump load. That zone valve opens either when the controller tells it to (over heat) while maybe also starting up a circulator, or it opens naturally when it loses power in a power outage. You could also use a controller with a surface mount probe rather than one that needs a temp well - much easier to install. Probe could go on the boiler outlet pipe or similar spot that would see hottest boiler temps.

 

[kravvelocity]

What exactly do you mean by 'there is no loop'? There should always be a loop, to somewhere. But not always to your zones/loads, no, if no call for heat.

If you are meaning rather a way to dump heat from the wood boiler - above post covers the basics. That requires a normally open zone valve, a controller for it, and a load preferably right above the wood boiler. If you can't plumb to one of your zones for that to use it for a load (my system uses my two second floor zones for that), you could add in another load just for that. (Pics don't give a good idea where the wood boiler is with respect to the oil & zones & rest of system). Say, maybe a big cast iron rad on the floor right above it. Should be right above to allow good convective flow. Because a proper dump zone will also be able to dump heat when the power goes out - which is also why you use a normally open zone valve for it, in between the boiler & the dump load. That zone valve opens either when the controller tells it to (over heat) while maybe also starting up a circulator, or it opens naturally when it loses power in a power outage. You could also use a controller with a surface mount probe rather than one that needs a temp well - much easier to install. Probe could go on the boiler outlet pipe or similar spot that would see hottest boiler temps.

Unless one of the zones is calling for heat there is no loop. I would need to leave one of the zones always open to complete the loop. If you look at the pic boiler 1. Zone 5 is the last pipe. That is the end of line with no way for the system to return water back up to the boiler unless something was calling for heat.

 

[peakbagger]

I have seen Honeywell aquastats with dual setpoints but havent messed with them. If you have a standard aquastat it may be easy to just swap it out with dual setpoint. The bummer with spare Tappings on wood boiler is sometimes they are hidden behind sheetmetal. Sometimes the easiest spot is on the outlet where a T can be installed.

 

[maple1]

Unless one of the zones is calling for heat there is no loop. I would need to leave one of the zones always open to complete the loop. If you look at the pic boiler 1. Zone 5 is the last pipe. That is the end of line with no way for the system to return water back up to the boiler unless something was calling for heat.

Yes - but isn't there a loop connecting the boilers? It doesn't take in your zones, but is a loop.

 

[kravvelocity]

Yes - but isn't there a loop connecting the boilers? It doesn't take in your zones, but is a loop.

It does tie into the oil boiler. The oil boiler pump only runs when one of the zones calls for heat, but that pump is cut off when using the wood. I tried to run both but the water was not being returned to the wood boiler and the temp dropped to 130 so the oil kicked in.

Would it just be safer and more effective to have a high efficiency wood insert put in the house? This this is something my wife is going have to keep an eye on during the day as well.

 

[maple1]

It does tie into the oil boiler. The oil boiler pump only runs when one of the zones calls for heat, but that pump is cut off when using the wood. I tried to run both but the water was not being returned to the wood boiler and the temp dropped to 130 so the oil kicked in.

Would it just be safer and more effective to have a high efficiency wood insert put in the house? This this is something my wife is going have to keep an eye on during the day as well.

You said in the OP that it all works fine. So not sure what the exact issue is that you're having or thinking about? Would seem to me that leaving everything alone would be the most effective thing to do. Your zone setup is a manifold setup. Quite common, that's what I have. 'No loop' would also apply to the oil boiler, if no zones were calling.

Also not sure about the mention of no return to wood boiler. If hot water is leaving it, return water has to be coming in the bottom too. From somewhere. Or did you mean that it was all circulating on the wood side (no return to oil), so the oil cooled below setpoint (130?) & cut in? My father has a wood/oil combo setup something like this. His is plumbed simply so the wood heated water flows through the oil boiler - the oil boiler still controls the whole system. And will cut in if the wood fired flow stops.

(I haven't take time to try to figure out all your pics).

 

[kravvelocity]

You said in the OP that it all works fine. So not sure what the exact issue is that you're having or thinking about? Would seem to me that leaving everything alone would be the most effective thing to do. Your zone setup is a manifold setup. Quite common, that's what I have. 'No loop' would also apply to the oil boiler, if no zones were calling.

Also not sure about the mention of no return to wood boiler. If hot water is leaving it, return water has to be coming in the bottom too. From somewhere. Or did you mean that it was all circulating on the wood side (no return to oil), so the oil cooled below setpoint (130?) & cut in? My father has a wood/oil combo setup something like this. His is plumbed simply so the wood heated water flows through the oil boiler - the oil boiler still controls the whole system. And will cut in if the wood fired flow stops.

(I haven't take time to try to figure out all your pics).

Correct it did work great when it's calling for heat. My concern is that when the zones aren't calling for heat there is no way for the water to return the boiler. I am guessing this will burn out the pump if its not pumping back. I have double and triple check to see if i am missing something but i don't think i am.

If you do see the pics. There is only 1 pipe that would allow the loop. That loop also would bypass the oil boiler tank so it would not be reading the temp. That pipe has the taco pump on it going in the wrong direction.

 

[maple1]

Are those pictures of everything as it is when burning wood? Re. valve orientations? Will study closer when I can. Preferably on bigger desktop screen but we just had a power outage.

 

[kravvelocity]

Are those pictures of everything as it is when burning wood? Re. valve orientations? Will study closer when I can. Preferably on bigger desktop screen but we just had a power outage.

Correct. I highlighted the routes it would take to and from the wood boiler. If anything is confusing let me know or if you want more pics.

Thanks!!

 

[kravvelocity]

Correct. I highlighted the routes it would take to and from the wood boiler. If anything is confusing let me know or if you want more pics.

Thanks!!

The valves in the pics are not correct. They were set for oil only in the pics

 

[maple1]

The valves in the pics are not correct. They were set for oil only in the pics

Does that mean you found the problem & fixed it? Or took pics when you weren't burning wood?

If not fixed, pics when burning wood wood help.

 

[kravvelocity]

Does that mean you found the problem & fixed it? Or took pics when you weren't burning wood?

If not fixed, pics when burning wood wood help.

no i mean the pics i took there are

Does that mean you found the problem & fixed it? Or took pics when you weren't burning wood?

If not fixed, pics when burning wood wood help.

No not fixed. I meant there are 2 yellow valves in the pics that would be changed. I marked with colors the flow that it would take. If its confusing when you look just let me know.

 

[maple1]

So if the yellow valves are switched, that should send all flow from your wood boiler, through your oil boiler before it hits the zones. On call for heat from zones. With no call, there would be no flow. That is a nice Buderus - which should be set up for cold start operation (only fires on demand - doesn't maintain heat all the time if no call for it). Which means the oil boiler shouldn't cut in at all under either circumstance. So not sure why the oil would be cutting in. Unless it isn't set up for cold start. And wood water somehow isn't going through it - which would be contrary to the valve description & red arrow flows.

What about those 2 gate valves? How are they set when burning wood?

 

[kravvelocity]

Yes that would send the flow from wood through the oil before it hits the zones. I am using the oil as backup. The temp on the oil is down to 120 so if the wood went out the oil could keep us from some heat going.

the gate on the return side is open for wood use. close for oil alone

the gate on the hot side is closed for wood/oil backup. open for wood only. open would bypass the oil

 

[maple1]

What controls your wood boiler circ? Does it only have one? Is there a bypass loop on the wood boiler also? Can't really see the whole thing. With the plumbing I do see, I would think a wood boiler circ would only run when the zone valves open. My old wood/oil combo also had a bypass loop with its own circ on it, that was controlled by boiler temp. it kept the boiler water mixed and prevented return water from being too cold before it hit the boiler.

Plumbing is only part of the equation. Controls being the other. Which we can't see much of. If you only have one circ on the boiler side, and it runs all the time there is a fire going, whether there is a call for heat or not - yes, that does not seem right, with the way it is plumbed & valved. To me. Maybe.

What prevents the green oil circ from running, when the wood boiler is running?

EDIT: And, maybe start with, what happens control wise, when a zone valve opens and calls for heat. I.e., what circ does that start running? And stop when heat call is done?

 

[kravvelocity]

there is 1 pump right off the wood. it is controlled by the aquastat on the boiler. dial on the left controls the damper. dial on the right controls the circ pump. i dont see any bypass loop any place. all the pipes run right down to the oil boiler.

 

[kravvelocity]

the blue valves might be where an auto bypass was and was cut out or they are just drains?

 

[maple1]

What is that right dial set at? Can't see in the pic.

So you know if there is a check valve in the green circ? Or anywhere else we can't pick out?

What happens to the green circ when the zones open & there is a call for heat? Is there switching of switches involved to go with the turning of valves?

 

[kravvelocity]

I have the temp set to 120. there is no check valve anyplace. If i open the valve before the green circ pump i can hear the water going back through it the wrong direction. I have a switch that shuts off that pump.