Primary Loop ?

Primary Loop ?

PostBy: Phil May On: Sat Dec 08, 2012 11:37 am

Is the bypass required when the primary loop only goes from top of boiler to the return ports. The primary loop on my new install will come out the top 90 to the front 90 to the side go through the flow check and air scoop 90 towards the back. There will be 4 secondary loops then 90 down to pump and return to the return ports. The whole primary loop will be less than 8' long. I would think the water would convect through it when the pump is off being that short. Also is there a any limit on how close the tees for the secondary loops can be together for hydraulic seperation. I was going to use 11/4" for primary loop and 1" for the secondary loops. I tried spacing them 6" but it makes the pipe way to long. Will 3" spacing work.
Thank
Phil
Phil May
 
Stoker Coal Boiler: EFM 700
Coal Size/Type: Buckwheat
Stove/Furnace Make: EFM
Stove/Furnace Model: 700

Re: Primary Loop ?

PostBy: steamup On: Sat Dec 08, 2012 11:47 am

Tees for a primary/secondary configuration can be as close as you can swing the pipe wrench. Rule of thumb says no more than 12" apart to keep pressure drop to a minimum.

I have a header where I used 3 and 4" nipples between the tees and it works fine. Made for a tight piping job though. Got to watch the valve handle clearances on the secondary piping.
steamup
 
Stoker Coal Boiler: Axeman-Anderson AA-130, Keystoker K-6
Hand Fed Coal Boiler: HS Tarm 502 Wood/Coal/Oil
Coal Size/Type: pea, buck, rice

Re: Primary Loop ?

PostBy: Phil May On: Sat Dec 08, 2012 11:53 am

Great on the spacing. How about the by pass it seems redundant to me for as short as my loop will be.
Phil May
 
Stoker Coal Boiler: EFM 700
Coal Size/Type: Buckwheat
Stove/Furnace Make: EFM
Stove/Furnace Model: 700

Re: Primary Loop ?

PostBy: 331camaro On: Sat Dec 08, 2012 12:26 pm

i did a short primary loop on my boiler and also put a pump on it to force the water thru it. this helps water temps from falling too quickly on the return side.
331camaro
 
Stoker Coal Boiler: Keystoker k6
Coal Size/Type: rice

Re: Primary Loop ?

PostBy: Rob R. On: Sat Dec 08, 2012 12:54 pm

If you have a flow check in the primary loop, it will not gravity circulate. You can skip the flow check, but if you don't have heat traps or flow checks on the secondary loops you might get gravity circulation into the zones. For the cost of a few tee's and a little bit of pipe, I would add the bypass into the plan.
Rob R.
 
Stoker Coal Boiler: EFM DF520
Hand Fed Coal Stove: Hitzer 50-93
Other Heating: Dad's 1953 EFM Highboy

Re: Primary Loop ?

PostBy: stoker-man On: Sat Dec 08, 2012 2:38 pm

The bypass loop helps to keep the water in the boiler a uniform temperature when it's idle. It's more important to return to both return ports.
stoker-man
 
Hand Fed Coal Boiler: 1981 efm wcb-24 in use 365 days a year
Coal Size/Type: Anthracite/Chestnut
Other Heating: Hearthstone wood stove

Re: Primary Loop ?

PostBy: Phil May On: Sun Dec 09, 2012 1:41 pm

Thanks for all the info.
Phil May
 
Stoker Coal Boiler: EFM 700
Coal Size/Type: Buckwheat
Stove/Furnace Make: EFM
Stove/Furnace Model: 700

Re: Primary Loop ?

PostBy: Rob R. On: Sun Dec 09, 2012 1:47 pm

When are you planning to have the 700 online?
Rob R.
 
Stoker Coal Boiler: EFM DF520
Hand Fed Coal Stove: Hitzer 50-93
Other Heating: Dad's 1953 EFM Highboy

Re: Primary Loop ?

PostBy: Phil May On: Mon Dec 10, 2012 1:43 pm

I hope soon. I have been doing some research and have decided to go with 11/2" primary loop. The 11/4" was right at max capacity and I want to be able to get all it has when I need it. where is a good place to get a 11/2" flow check and a 11/2" air scoop. Changing the size means I am going to have to buy some new stuff. I am still planning on using the 2 11/4" returns. With the bigger pipe they should balance better. Has anyone ever had problems with the last zones on the primary loop not getting hot enough water? I am a little concerned about this. I am going to put my biggest load last in the loop (60k btu shop with radiant heat) if the shop is a little colder it would be better than the house. the total heat load calculated to 181,000 btu. Plus I am going to add a couple taps with plugged valves for any future brain farts that might occur.
Phil May
 
Stoker Coal Boiler: EFM 700
Coal Size/Type: Buckwheat
Stove/Furnace Make: EFM
Stove/Furnace Model: 700

Re: Primary Loop ?

PostBy: JRDepew On: Mon Dec 10, 2012 2:23 pm

Phil May wrote:I hope soon. I have been doing some research and have decided to go with 11/2" primary loop. The 11/4" was right at max capacity and I want to be able to get all it has when I need it. where is a good place to get a 11/2" flow check and a 11/2" air scoop. Changing the size means I am going to have to buy some new stuff. I am still planning on using the 2 11/4" returns. With the bigger pipe they should balance better. Has anyone ever had problems with the last zones on the primary loop not getting hot enough water? I am a little concerned about this. I am going to put my biggest load last in the loop (60k btu shop with radiant heat) if the shop is a little colder it would be better than the house. the total heat load calculated to 181,000 btu. Plus I am going to add a couple taps with plugged valves for any future brain farts that might occur.


I have had good luck ordering from pexsupply.com. The prices seem good, fast shipping, and returns are easy. One of my coworkers got the wrong part from them twice but I've never had it happen to me.

Joe
JRDepew
 
Stoker Coal Boiler: EFM 350

Re: Primary Loop ?

PostBy: Rob R. On: Mon Dec 10, 2012 2:37 pm

Thumbs up for pexsupply, anything I order from them before 3 pm I get the next day. Good prices too.

Your primary loop size seems fine to me...especially since the largest zone happens to be last in line, and can use low temperature water for the radiant slab.
Rob R.
 
Stoker Coal Boiler: EFM DF520
Hand Fed Coal Stove: Hitzer 50-93
Other Heating: Dad's 1953 EFM Highboy

Re: Primary Loop ?

PostBy: Phil May On: Mon Dec 10, 2012 5:05 pm

I use pex supply also but they dont carry much for 11/2". Mostly 11/4" and smaller also lately a lot of items are out of stock.
Phil May
 
Stoker Coal Boiler: EFM 700
Coal Size/Type: Buckwheat
Stove/Furnace Make: EFM
Stove/Furnace Model: 700

Re: Primary Loop ?

PostBy: Rob R. On: Mon Dec 10, 2012 5:40 pm

You could always try your local plumbing supply house. Pexsupply does have some of the 1.5" stuff you need, but a cast iron air scoop and flowcheck is going to have a hefty shipping charge.

http://www.pexsupply.com/Taco-433-5-1-1 ... -3514000-p

http://www.pexsupply.com/Bell-Gossett-1 ... -8602000-p

http://www.pexsupply.com/Taco-222-6-1-1 ... -1993000-p

:idea: Use a circulator with an internal flow check for the primary loop.
Rob R.
 
Stoker Coal Boiler: EFM DF520
Hand Fed Coal Stove: Hitzer 50-93
Other Heating: Dad's 1953 EFM Highboy

Re: Primary Loop ?

PostBy: franpipeman On: Tue Dec 11, 2012 9:40 am

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Here is my primary loop. I dont use a pump but I constructed a 3 inch welded header and get great gravity circulation. No flow control on primary. I only have a minimal load right now but have the potential to take a various other secondary loops . I have of course tied into both return ports. I installed a butterfly valve to balance the flow though theortically I shouldnt have to do so. I have insulated and installed the boiler jacket and piping which i am a big advocate of. I have the luxury or scourge of being a retired steamfitter I guess sometimes I just have to feel those welding sparks getting in my ear and making the funny sound they do with the end result of me screaming outin exctasy or pain one or the other. I have installed balancing valves on the return ports to assure flow is divided.
franpipeman
 
Stoker Coal Boiler: efm 520 stoker fitzgibbons pressure vessel
Hand Fed Coal Stove: harman, russo
Coal Size/Type: rice

Re: Primary Loop ?

PostBy: KLook On: Tue Dec 11, 2012 9:50 am

I am assuming with your primary loop you are using the closely spaced t's for the output and return. With nothing more then gravity causing a flow, how do you prevent the return water from just being sucked back into the output side? Or is the flow and size of the 3 in pipe enough to prevent this? Spacing from output to input critical? Once the temp is up to maximum through out the boiler and primary loop, does the flow stop or get seriously reduced?

Kevin
KLook
 
Stoker Coal Boiler: Harman VF 3000
Coal Size/Type: rice, bagged, Blaschak
Stove/Furnace Make: Harman (Back In Maine)
Stove/Furnace Model: VF 3000