I Have Read ? About Series Vs Parallel.

Hi, I hav elooked at the pictures in this post How Do You Connect Two Boilers?,
1.if I hook it up parallel will my oil boiler still kick on automatcialy if the temp drops below a set level, if it k6 went out or could not keep up?
2.also if I where to shut the k6 down and where to heat with oil would I still heat the coal boiler also, or is there a bypass? parallel I can see the bypass but inseries I can not see how that would work?
3.I thought I had to use a circulator to keep the water flowing between both boilers all teh time I don't see that in teh pictures.
4.In the parallel set up is the coal boiler heating the oil boiler? or is it just bypassing it?

I am trying to figure out which set up is best. Thanks

I ran my oil and coal units in series. Yes the coal is heating the water in the oil unit. I added a circulator that brings hot water from the coal to the oil unit. I have it controlled by a L4006A aquastat. When the temp in the oil unit drops enough the circulator comes on and then shuts off when the oil unit is back up to temp. I have a DHW coil in the oil unit that feeds my electric water heater so I want to keep the oil unit hot.

You can add a manual bypass pipe and valves to eliminate the oil unit but that renders it useless as an automatic backup. I'm wondering if you could set up a bypass with zone control valves that monitor the water temp that could automatically add the oil unit into the system as needed. It probably could be done but I'm sure it would cost big $$$ for all of the controls.

My coal unit can put out much more BTU's than my existing oil unit so I don't anticipate useing the oil unit except for emergencies or if we need to leave the coal unit unattended for any length of time.

I believe the way I have my system set up is probably not the most efficient way but I addressed what I believe to be my concerns at the time. I guess I'll find out this heating season if my method was worthwhile.

Any more info on my above ? would be great, I only want to do it once and want to do it right, I would rather spend a little more now. Thanks

JOE.G wrote:Hi, I hav elooked at the pictures in this post How Do You Connect Two Boilers?,
1.if I hook it up parallel will my oil boiler still kick on automatcialy if the temp drops below a set level, if it k6 went out or could not keep up?
2.also if I where to shut the k6 down and where to heat with oil would I still heat the coal boiler also, or is there a bypass? parallel I can see the bypass but inseries I can not see how that would work?
3.I thought I had to use a circulator to keep the water flowing between both boilers all teh time I don't see that in teh pictures.
4.In the parallel set up is the coal boiler heating the oil boiler? or is it just bypassing it?

1. Yes, depending on how it is plumbed and wired.
2. No, depending on how it is plumbed and wired.
3. Again, it would depend on the install.
4. Not in the drawing that is in the link you provided, the two units operate independently.

Could you help me out then, I want it to be efficent, I want the oil boiler to come on only if it needs to and to be able to do it automaticaly. I also would like to not have to heat both boilers ( I probably will shut the coal down for the summer and use the oil)

Please

All you do is provide a separate thermostat to each unit and program one at a lower temp then the other.

JOE.G wrote:I want the oil boiler to come on only if it needs to and to be able to do it automaticaly. I also would like to not have to heat both boilers ( I probably will shut the coal down for the summer and use the oil)

Without huge money and complications, it can't be totally automatic. With coal there is some labor. You have to be there to take out the ashes, so while you're there you'll have to shut a valve or two, turn on or off a switch or two in order to go from one to the other and keep the other cold.

If you want the oil to take over automatically, set the coal boiler aquastats 20 degrees higher than the oil. The oil will never kick in unless the coal goes out. If you decide to not burn coal for a season you'll have to bump the oil aquastat up that 20 degrees to get full heat.

Joe G.,

I too want my oil to come on automatically. I am in the process of puting an EFM 520 in place. I haven't wired it up yet so my plans are only in theory. Here is what I am planning on doing.

I have an L6006A aquasta that I am going to use as my outfire dectection. This switch is double ploe so there is a normally open and a normally closed set of contacts along with the common contact. The aquastat will be set to swich AC off to the stoker when the coal boiler drops below 140* (or whatever temp you set it at). When it does it will supply AC power to the oil boiler to fire it up. Along with the aquastat I plan to wire in 4 AC switches for auto/manual control and boiler main AC disconnects. I haven't sat down and put it all into a schematic. As I stated this will work in theory (in my mind). I will be using a circulator pump on each boiler as well as check valves to keep feedback from the non-operational boiler.

PM me if you want to discuss this more. I'm usually on here once a day during the week. On weekends I've been busy getting the coal boiler in place and hooked up. I hope to finish this weekend and fire it up.

Freddy what do you mean shutting vavles, I know in teh summer I would like to shut a vavle or 2 and use just the oil, Also how are you guys doing the piping t in or what Thanks

check out a tekmar 262 controller which controls both boilers and a host of other features. also there are other tekmar controller that may better suit your needs.

http://www.tekmarcontrols.com/prod/262.shtml

also I'll draw a simple parallel design

added: here is comparison chart of the features of each unit.

http://www.tekmarcontrols.com/function/boiler.html

this goes for anyone looking at controllers, a nice to feature to have and helps to reduce over-rides after the boiler shuts down is (Boiler Post Purge) which contunies to run the pump after the boiler shuts down. It moves heat out of the boiler into the zone and moves cold water back into the boiler to pick up the heat left over from firing.

JOE.G wrote:in teh summer I would like to shut a vavle or 2 and use just the oil,

And have the coal boiler cold? Then plumb them parrelell. That allows you to use one, or the other.

In your original paragraph you show a link to another post. Coaledsweat & Yanche give good info there. Re-read it until you understand what they're saying.

Maybe some pics of the oil system you have would help? It might make a difference if it's one zone, coil hot water, vrs many zones and indirect hot water.

I have 3 heat zones now and 1 dhw zone for a indirect, if I hook it up parreal does the oil boiler still get heat from the coal boiler? if not what keeps it from firing if the low limit is reached? if it does get heated by the coal if I turn the temp down or hook up a seprate termostat it should still kick on by it self correct? Anyone have some good picks of series and parellal set ups? what parts do I need?

Hi Joe

there are many threads about series parallel with diagrams on here. You might want to do a search as I am sure it will yield plenty of info on that.

I personally would recommend you go buy a few books related to these topics first. then come back and ask what you didn't get answered there.

that is exactly what I did and it has paid huge dividends. I had never dealt with heating systems ever prior to this fall.

I basically just finished installing my EFM 520 the way I felt it would work best.

You will get answers to this i'm sure. but I think you might also turn some people off from helping you. Nothing in life is free. Make the effort to learn about what you are doing and you'll be that much further ahead on your install.

Or call a plumber for an estimate. In retrospect on my job. I would have called a plumber!!! been done in a week or less. Instead It took me 5 weeks of working about 2 or 3 hours per night after my day job... there is something to be said for that!

and as I mentioned on the other side of the coin I now know my heating system inside and out! so I guess it was worth it!!

PS Not trying to offend you here. Just suggesting.