New DIY Boiler Install Questions

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Old 01-29-10, 11:04 AM
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Smile New DIY Boiler Install Questions

Hello All,

I just needed some advice on a new boiler install. Here are some details so you guys can look at.

1. 1567 Sq. Ft Cape Cod
2. Converted from coal to gas and was gravity system with 2 return and 2 supply piping
3. System is 2.5" to 3" main on return and supply and sized down to 1.25" to boiler
4. Steel expansion tank in floor joist above boiler
5. No air separator that I can see
6. 1 Taco 007-F4 circulator on return pipe close to boiler
7. No bypass installed
8. Old boiler is 27 year old Smith Series-8 converted from oil to gas
9. 1 zone system
10. Heat loss calc. done on house and was 79k, should get better when the attic insulation is upgraded.

I want to buy a Smith GV100-5 that my friend is selling me. It’s brand new, never been used and the GV100-5 has an input of 100 MBH and 84MBH DOE heating capacity, so that should work fine.

My question is regarding piping. Should I go with P/S or just stick with one circulator of the supply and go with the bypass? From what I've read on one of Dan Holohan's books is that I should go with a high flow rate circulator vs. a high head one. What would be the best way to go with this old system? I am planning on installing an indirect water heater too.

What do you guys think?
 
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Old 01-29-10, 04:03 PM
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We always suggest you tighten the structure first, reduce the heat loss and buy a smaller boiler.
Either a boiler bypass or p/s with a valve on the supply side of the boiler to control flow through the boiler is OK.
You won't need too large of a pump as you only need to move 8 gpm. That system has a low resistance to flow. A Taco 007 may be enough.
You may want to reduce the pipes in and out of the boiler to 1" in you do p/s. Leave it 1/1/4" if you do a boiler bypass and use 1-1/4" for the bypass with a valve below the bypass to reduce flow through the boiler.
I know you are getting a deal on this boiler but sounds like a mod/con would be a better choice. Check the radiation and see how much you have as compared to the heat loss. With the pipe sized you stated I bet it was a gravity system. These systems usually worked on water temps usually around 100f.
 
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Old 01-29-10, 05:36 PM
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Thanks for the reply rbeck.

That was the heat loss assuming the house had all new windows and upgraded insulation in the attic. The old boiler was rated at 151MBH.

Are the 8 gallons only taking into account the boiler? What about the system? Wouldn't I need to move as much water as fast as possible, since the system has 2.5 to 3" mains and 598.5 sq ft of EDR and low head? I think that's something like 89k of btu/hr of radiation. There's a lot of water in this system too.

I was thinking of going with p/s and having the secondary pump run when the boilers primary circuit reached a high limit of 170 degrees. I wanted to keep the boiler above the condensation point too. The 1" boiler piping was exactly what I decided to go with.
 
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Old 01-29-10, 06:22 PM
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Your system sounds very similar to mine. I recently had a Burnham ES2 105k BTU input installed. I don't have the Taco 007, but a Grundfos which I think is similar in performance. I have cast iron radiators on an old gravity system.

With a smaller boiler, the water will not heat up as fast and you don't want it to go through the boiler too fast or it won't pick up the heat.
 
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Old 02-01-10, 10:20 AM
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Thanks for the reply!

Did you install the system yourself?

So, you are using just one pump? I was planning on going with p/s or a single pump off of the supply, but I want to run an indirect water heater too. I'm just looking for advice on what would be the best way to do this myself, since we had saved up for a new boiler and got quotes for installation, but since my wife got laid-off a couple of months ago, well our savings have hit bottom.

drooplug - Does your system have 2 return and 2 supply also? For my project I was going to connect 1 return to 1 supply and use the remaining return and supply for the boiler. If I went with the single pump I was going to use the B&G Series 100, but from what you're saying the pump is too fast. Even if the near boiler piping was cut down to 1"?
 
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Old 02-01-10, 03:22 PM
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Stop,
Pipe the two returns together.
Pipe the two supplies together.

Do P/S or a boiler bypass is up to you.

If your load is 84,000 btu then you need only move 8.4 GPM. Moving more will net you little more than a higher power bill.

If it was me, and I didn't go mod con, I would do p/s piping with a good boiler control that will look after boiler protection and domestic hot water generation.

Dump the air cushion tank in the ceiling for a pre-chraged type.
Thats about as simple as it gets.
TO
 
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Old 02-01-10, 05:31 PM
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Originally Posted by ezra18042 View Post
Thanks for the reply!

Did you install the system yourself?

So, you are using just one pump? I was planning on going with p/s or a single pump off of the supply, but I want to run an indirect water heater too. I'm just looking for advice on what would be the best way to do this myself, since we had saved up for a new boiler and got quotes for installation, but since my wife got laid-off a couple of months ago, well our savings have hit bottom.

drooplug - Does your system have 2 return and 2 supply also? For my project I was going to connect 1 return to 1 supply and use the remaining return and supply for the boiler. If I went with the single pump I was going to use the B&G Series 100, but from what you're saying the pump is too fast. Even if the near boiler piping was cut down to 1"?
I did not install the system myself. I have two heating zones now. The first floor is the old gravity setup and it does have two supply and return lines, one for each side of the house. They way my piping is now, there is a 3/4" pipe that comes off the boiler manifold and then splits to serve the two supply pipes. The opposite occurs for when the returns come back to the boiler.

My second zone is new. It serves the second floor radiators that were added around 1950 and were supplied off the old gravity system.
 
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Old 02-02-10, 05:10 AM
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Thanks TO, we really wanted to go mod/con, but with situation we are in that idea got blown out of the water. It would of really cut our long term costs.

Going with the p/s and the Smith boiler for the spring is what our budget can handle. Plus the Smith is being sold with an extra 007, so that helps out. I was thinking of getting the Tekmar 260 to control everything. The Smith boiler is a power vented unit so that helps out because I'm almost sure the previous conversion was not done properly and the chimney was lined, so we can vent through the wall.

drooplug - so the whole system is radiators and from what you are saying it has no p/s piping?
 
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Old 02-02-10, 05:59 PM
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Originally Posted by ezra18042 View Post

drooplug - so the whole system is radiators and from what you are saying it has no p/s piping?
That is correct. I plan on installing a bypass. I haven't worked with black pipe before so I am reluctant to do it during the heating season. I'm trying to get my friend to lend me a hand. Haven't heard much as to whether he was willing or not.
 
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Old 02-03-10, 06:47 AM
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drooplug - I don't hink you have to go with balck pipe, it can be done in copper and if I'm correct you have to install the correct size pipe with respect to your near boiler piping.

Can anyone shed some light on that?
 
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Old 02-03-10, 02:14 PM
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EZRA is correct. For a forced hot water system you do not have to go with black iron. Copper is fine, as that's what any plumber would install. As was mentioned, just make sure your near-boiler piping is sized correctly.
 
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Old 02-03-10, 03:09 PM
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The bypass should be full sized and I think Drooplug has all iron pipe and no copper so iron would be better. Just remember to have a valve below the bypass to control the flow through the boiler.
I would not change the old tank between the floor joists. I don't like to create maintenance. The old style tanks are maintenance free tanks if properly installed.
Again p/s or boiler bypass works well. If using p/s have a valve on the boiler piping to reduce the flow through the boiler. It needs to be on the discharge side of the pump.
Either p/s or boiler bypass will work the system temperature lower without controls. It is what I call poor man's OD reset. Not near as accurate but saves fuel. The lower water temps work best with a larger water volume system such as CI rads.
 
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Old 02-03-10, 04:47 PM
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That is correct. I have all black pipe. The changes are minor and patching in copper would make it look a little silly.
 
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Old 02-04-10, 06:43 AM
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Sounds good

Rbeck - when you say that the bypass should be full sized, do you mean whatever size are the inlet and outlet of the boiler are? For the old steel thanks they do make an in tank aerator or something like that? Would it be better to have a in-line or the in tank one? As for the valve, it should be on the discharge side because you don't want to starve the pump?

drooplug - yeah it would look silly to have black pipe and then copper.
 
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