How to Plumb Two Boilers in Series

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fstalfire
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Post Mon. Apr. 28, 2014 10:07 pm

I have an oil fired boiler currently and have just purchased a coal boiler, I would love to be able to keep the oil unit hooked up and put the coal one next to it and connect it to the oil unit to utilize the auto fill and circulators currently in use as well as the thermostat hooked to the oil unit.......Is this possible? if I tapped into the water lines from the oil unit wouldnt the coal unit keep the water in the oil unit boiler at temperature, essentially doing the work of the oil burner without it being on and taking advantage of the thermostat and cirrulators plus having a back up if I run out of coal or travel for more than a few days?

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whistlenut
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Post Mon. Apr. 28, 2014 10:21 pm

Do a search, all the info is already here. The answers to your questions are: Yes, YES, and Yes!

Welcome aboard! The search box is in the upper right corner...............

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coaledsweat
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Post Tue. Apr. 29, 2014 6:44 am

Yes. You will need an additional expansion tank or one larger. Keep in mind you'll have some parisitic loss from the oil burner's chimney. Not a real big deal with the savings. A automatic stack damper can reduce that to next to nothing.

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Rob R.
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Post Tue. Apr. 29, 2014 12:34 pm

fstalfire wrote:I would love to be able to keep the oil unit hooked up and put the coal one next to it and connect it to the oil unit to utilize the auto fill and circulators currently in use as well as the thermostat hooked to the oil unit.......Is this possible?
It sure is, I have done it a few times. I prefer to use two closely spaced tee's in the supply rise on the oil boiler, but that isn't possible on every installation. If you post some pictures of your existing piping we can probably come up with some ideas.

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Sting
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Post Tue. Apr. 29, 2014 1:02 pm

A "Series' instillation is the quickest cleanest simplest way to "get-er-done" and there is nothing wrong with that

Please note = I didn't use the word 'BEST'

Close spaced Tee's ??? WOW here we go with Primary/Secondary school again :shock:

I used to recommend that to folks that didn't want the drama - didn't want the expense - didn't want the extra pumps and all that jazz -- and most often that didn't end well

It Depends :P


fstalfire
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Post Tue. Apr. 29, 2014 8:10 pm

So...I have moderate Plumbing skills....is a series connection something I could handle or should I call a plumber? and, what is the installation?

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coaledsweat
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Post Tue. Apr. 29, 2014 8:51 pm


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Sting
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Post Tue. Apr. 29, 2014 8:53 pm

read some of the above post links
I forgot most of them
maybe read a little of this

Post by Sting - New Member

if you understand the stuff = then yes U can

fstalfire
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Post Tue. Dec. 09, 2014 11:01 pm

Hi guys....so I posted a question about dual boilers a few months ago and got some great info....the summer and fall came and went and I didnt get a chance to work on it and now its time.....I've attatched some pics of my current oil boiler and a pic of the back of my boderus coal boiler...I think I just want to hook it up in series but I've noticed the oil boiler has some carzy plumbing and it looks like there is a loop between the hot out and the return which I don't understand....can I just put a "T" in the supply and return of the oil boiler and hook that to my coal and leave the rest alone? Also, the coal boiler has 2 connections at the top...is the small one the fill and the large the supply?
Attachments
oil1.jpg
oil2.jpg
coal1.png

lzaharis
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Post Tue. Dec. 09, 2014 11:28 pm

First, hire a plumber :idea: , second, your boilers are close enough
that you can plumb the boilers in parallel and get rid of that snakes
nest of plumbing and get the right size bladder expansion tank.


fstalfire
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Post Wed. Dec. 10, 2014 12:02 am

Ok, so a friend is a plumber and has offered to help out...second, you think its better in parallel not series?....I have only one chimney flue

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coaledsweat
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Post Wed. Dec. 10, 2014 6:39 am

fstalfire wrote:Ok, so a friend is a plumber and has offered to help out...second, you think its better in parallel not series?....I have only one chimney flue
I prefer parallel. In series you have a parisitic loss to the chimney from the unused unit unless you use a damper or remove and block off the stovepipe. I also prefer a seperate pump on each giving you 100% backup if something goes wrong.

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Sting
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Post Wed. Dec. 10, 2014 7:38 am

fstalfire wrote:I have only one chimney flue
Then you will only use one appliance or the other and orientation options do not matter

lzaharis
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Post Wed. Dec. 10, 2014 3:17 pm

fstalfire wrote:Ok, so a friend is a plumber and has offered to help out...second, you think its better in parallel not series?....I have only one chimney flue
==================================================================================================

parallel is better in my opinion,

if you have only one flue, code requires
one flue for each appliance, unless the unit
is a dual fuel unit.

THE OPTION,

is to simply use one or the other heating unit and
physically disconnect the units flue piping and
set it aside and put the other flue pipe connection
in its place.

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