Whats the difference Zone Valve and a circulator pump per zone

[mpilihp]

In looking at the piping for putting an add-on Marathon wood boiler in with our existing oil boiler by the diagram on their website:

http://www.marathonheaterco.com/diagram_addon.html

And the difference which concerns me is their setup utilizes a single circulator pump for ALL heat zones and seperate zone valves whereas my house has seperate zone circulator pumps. My concern is when the ZONE pumps are OFF and the wood boiler circulator pump is running to heat the oil boiler tank are these ZONE pumps BLOCKING and not allowing the heated water to circulate through the heat zones too?

If they are NOT blocking and letting heated water through do I need to add zone valves in line with the zone circulator pumps?

THanks

~ Phil

 

[Bob Rohr]

I don't understand the flow or control logic in that drawing?

On a call for heat the zone valves open and call on the upper pump only?

So which boiler gets flow and how much? If the wood boiler circ comes on then two circs are in series?

The bull headed tee at the bottom should be re configured also.

I don't see a means for return protection on the wood fired? maybe with low mass emitters like baseboard that may not be an issue. If you have radiant slabs, or a thirsty buffer tank you might consider return protection for the wood fired.

Really if a buffer is ever in the plan, the oil fired boiler should not charge the buffer, but go directly to the load.

I think they are over simplifing that piping. You may be able to intergrate the add on boiler with the piping you have in a better piping.

hr

 

[Nofossil]

The Marathon diagram makes no sense to me, either. In a zone valve based system, I'd plumb the two boilers in parallel, each with their own circulator, both drawing from the same return and feeding the same supply. The circs will have to have integral check valves to prevent backflow. This is what I do. I have a diagram on my web site - link in my signature below.

Larger / more complex systems will be more likely to have one circulator per zone rather than zone valves. This approach seems to make sense especially in the case where the heat loads require different flow rates, or where there are many (more than 5 or so) heat zones. There's a good explanation of this approach in a sticky at the top of the boiler room section.

 

[BrownianHeatingTech]

I don't understand the flow or control logic in that drawing?

On a call for heat the zone valves open and call on the upper pump only?

So which boiler gets flow and how much? If the wood boiler circ comes on then two circs are in series?

My assumption is that the top pump is used when the oil boiler is running, and the bottom pump (drawing through the top pump) when the wood boiler is running.

Moving the top pump to the left side of that tee would make more sense, so neither pump is in the common piping. That would make it a strict parallel setup.

Not a very good diagram, as-is. Adding a bypass circ would be a good return protection method. Run it into the common piping, and you would have return protection for either boiler. Never a bad idea.

Joe

 

[mpilihp]

Hello thanks for the input and access to your diagram of how your system is set up. The marathon wood boiler I have was set up and running like how the diagram displayed. How it worked as it was discribed to me.

No zone calling for heat.
If the temperature in the wood boiler is lower than the oil boilers low burner turn on temp the wood boiler loop circulator pump is off.
If the temperature in the wood boiler is higher than the oil boiler's low burner tur on tem the wood boiler loop circulator pump is turned on.
This cycles the heated water in the wood boiler down and into the SUPPLY pipe of the oil boiler and around, in a reverse cycle that water normally cycles through the oil boiler.

A heat zone calling for heat and water is hotter in wood boiler than oil boiler.
When this happens the flow of heated water through the oil boiler will reverse and heated water from both the oil and wood boiler will go up through the calling zone. THen the return from the zone will come back and into both the oil and wood boiler.

Im very new to this and I understand this is a simplified installation compared to others, I am going to incorporate a heated return path so that the return into the wood boiler is not as cold and hopefully will lessen/prevent condensation in the wood boiler as Ive been told this is a source of moisture and rusting.

I still have the open question of whether or not a zone circulator pump acts as a zone vave and when its off if no water can flow through if pushed by another circulator pump (the loop circulator)

Another simple design but alittle more complicated is the setup used by NewYorkBoilers. Its diagram is here at the bottom of this PDF
(broken link removed to http://www.newyorkerboiler.com/pdf/WC%20FuelSaver.pdf)

This diagram has some icons that are not labeled and I wasnt sure what some were, the circles on the pipes besides the boilers with an arrow below them im assuming is a backflow preventer?? On top of the fuelsaver boiler is a black circle with a white square in it, Im guessing thats the circulator pump?

THanks

~ Phil


Thanks.

 

[Willman]

I still have the open question of whether or not a zone circulator pump acts as a zone vave and when its off if no water can flow through if pushed by another circulator pump (the loop circulator)

You would need circs with internal flow checks to keep ghost flow from other circs. Check out circs with IFC.
Will

 

[mpilihp]

Hi Willman thanks, I will check and see what make/model I have and see if they are IFC type.

I am also working on a diagram of my current setup and my proposed piping and hopefully it will be easier for me to understand everyones suggestions.

THANKS!

 

[Bob Rohr]

Hello thanks for the input and access to your diagram of how your system is set up. The marathon wood boiler I have was set up and running like how the diagram displayed. How it worked as it was discribed to me.

No zone calling for heat.
If the temperature in the wood boiler is lower than the oil boilers low burner turn on temp the wood boiler loop circulator pump is off.
If the temperature in the wood boiler is higher than the oil boiler's low burner tur on tem the wood boiler loop circulator pump is turned on.
This cycles the heated water in the wood boiler down and into the SUPPLY pipe of the oil boiler and around, in a reverse cycle that water normally cycles through the oil boiler.

A heat zone calling for heat and water is hotter in wood boiler than oil boiler.
When this happens the flow of heated water through the oil boiler will reverse and heated water from both the oil and wood boiler will go up through the calling zone. THen the return from the zone will come back and into both the oil and wood boiler.

Im very new to this and I understand this is a simplified installation compared to others, I am going to incorporate a heated return path so that the return into the wood boiler is not as cold and hopefully will lessen/prevent condensation in the wood boiler as Ive been told this is a source of moisture and rusting.

I still have the open question of whether or not a zone circulator pump acts as a zone vave and when its off if no water can flow through if pushed by another circulator pump (the loop circulator)

Another simple design but alittle more complicated is the setup used by NewYorkBoilers. Its diagram is here at the bottom of this PDF
(broken link removed to http://www.newyorkerboiler.com/pdf/WC%20FuelSaver.pdf)

This diagram has some icons that are not labeled and I wasnt sure what some were, the circles on the pipes besides the boilers with an arrow below them im assuming is a backflow preventer?? On top of the fuelsaver boiler is a black circle with a white square in it, Im guessing thats the circulator pump?

THanks

~ Phil

I really don't see any reason for flowing through an unfired boiler regardless of the direction. A portion of your energy will just go up the flue pipe. It is very easy to pipe those so that there is never flow through the unfired one. I'm not sure why manufacturers continue to ignore that simple piping change?? Guess it's not their wood or oil to waste

But you REALLY don't want the oil fired boiler running heat through the un-fired wood boiler, as it becomes more of a cooling tower at that point.

If the two circs are in series the internal check will not stop flow, nor would you want it too. If the two circs pipe off a common pipe the checks prevent backwards flow.

hr


Thanks.

 

[BrownianHeatingTech]

I really don't see any reason for flowing through an unfired boiler regardless of the direction. A portion of your energy will just go up the flue pipe. It is very easy to pipe those so that there is never flow through the unfired one. I'm not sure why manufacturers continue to ignore that simple piping change?? Guess it's not their wood or oil to waste

Lots of folks (unfortunately) still have warm-start boilers with domestic water coils installed. So the oil boiler has to stay warm in order to produce hot domestic water.

If folks have the funds, replacing that with a cold-start boiler and tank is always a good bet, but a lot of folks don't have the funding to replace the oil boiler...

Joe

 

[Redox]

I really don't see any reason for flowing through an unfired boiler regardless of the direction. A portion of your energy will just go up the flue pipe. It is very easy to pipe those so that there is never flow through the unfired one. I'm not sure why manufacturers continue to ignore that simple piping change?? Guess it's not their wood or oil to waste

Lots of folks (unfortunately) still have warm-start boilers with domestic water coils installed. So the oil boiler has to stay warm in order to produce hot domestic water.

If folks have the funds, replacing that with a cold-start boiler and tank is always a good bet, but a lot of folks don't have the funding to replace the oil boiler...

Joe

One quick and cheap way would be to put in a conventional electric water heater and a bronze circulator to heat the tank with the existing domestic coil. Should be less than $500 and quick payback.

Chris

 

[mpilihp]

Hi all thanks for the feedback, yes we are doing this on the low dollar wise. Our oil boiler is im guessing as it was called a warm start, its belly is always kept warm and for domestic water.

During the winter there wont be alot of time when the oil boiler would be heating the wood boiler's belly as we currently supplement with a wood stove and keep it cranking every day for the most part.

But... couldnt I utilize a loop circulator pump for moving water through the wood boiler that has a IFC inside it. That way when the water temp in the wood boiler is less than the oil burner turn on temp the loop circ will be off and blocking flow through the wood boiler correct?? Or instead of manual isolation ball valves install zone valves to OPEN whenever the loop circ pump is on and close when the loop circ is off (meaning the temp in the wood boiler is too low to heat the oil boiler)

During the off season when its not needed I would close it off with the isolation valves, manual intervention but easy to do.

This is our first step in trying to save $$ by using less oil, we used about 500 gallons of oil and hope to drop that down by half, I may be dreaming but thats our hope.

If oil is $4 a gallon it will pay for the wood boiler completely!!

WHen I do the piping changes I am going to set it up to allow adding additional zones on easily so I could do a domestic hot water storage tank as a zone, then we could add a water tank that could also be heated via a different source, ie a on demand gas heater which are not that expensive. We have gas now for cooking. Or leave things as is and in the off heating season turn the boiler off completely and heat domestic HW just with an on demand gas unit. Any pros/cons there??

Thanks again guys.