Boiler operating temp??


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Old 12-11-22, 08:49 AM
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Boiler operating temp??

A good friend is hv'g issues with his newly installed hot water boiler. (Not a summer/winter unit) family member install!!! 2 pipe black suppy/return radiator system tied in with 1.5 supply n 1.25 return [copper] brand "Slant Fin" 100+in / 88k out - gas fired.... ***ISSUE*** WATER NOT EXCEED'g 145⁰ BOILER WI NOT CYCLE N CONTINUES TO RUN UNTIL STAT IS SATISFIED!! N RELIEF BLOWS [30psi] ISSUES I FOUND!! BAD WATER FEED,- (manually fed) AIR SCOOP REVERSED, EXPANSION TANK TOO SMALL!! 1700 sq foot hse. Believe return return is too large n wayer is not staying in the tank long enough to heat?? 145⁰ out - 118⁰ return. +/- 4⁰ believe if i repipe return to 0.75 black n slow return should raise temp to stayify aquastat. Hv NEW scrap black pipe, WENT I INSTALL NEW FEED N BACK FLOW N REVERSE AIR SCOOP N GO WITH A $30 AMTROL [4,5] XPAN TANK. HAS A 2GAL ON SYSTEM NOW. WHAT IS UR OPION?? RETIRED N LACK THE BIG $$$ TOOLS I HAD ACCESS TO FOR PROPER DIAGNOSTIC. THKS
 
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Old 12-11-22, 10:23 AM
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Welcome to the forums.

Sounds like a few mistakes were made.
Not sure what you are looking for or what help we can give you based on your verbal description.
Pictures are very helpful..... How to insert pictures.

Typical hot water out temp should be closer to 180
 
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Old 12-11-22, 11:57 AM
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Boiler Operating temp

Reduce volume speed of water n maintain in heat exchanger longer to increase temp. Want to reduce via return side in which will not increase boiler psi since on suction side. Need water to come up to operating temp. Or at least 20⁰ increase. Cast iron RADIATORS.
 
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Old 12-11-22, 12:04 PM
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Temp

Fyi. 2 pipe SUPPY N RETURN system. NO MONO FLOW TEE'S!!
 
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Old 12-11-22, 01:01 PM
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You should not have to change pipe sizes to get satisfactory results. Pictures will help us to see how the boiler is installed and piped and whether there is a bypass.

I run my gas-fired Burnham ES-2 at 150 degree set point (and 30 degree differential) for cast iron radiation and have no problem with either the space heat or boiler temps and cycles. My piping is up to 2" black since the system was originally gravity but is now pumped through smaller connections at the boiler.
 
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Old 12-11-22, 01:28 PM
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As suggested in post 2 pics would be very helpful as I cannot find your boiler. With cast iron rads or you should have a minimum of a #60 extrol because of the high water content which is why your relief valve is blowing off. The expanded heated water doesn't have enough room so pressure is built up in the closed system and blows at 30psi.

You do not need monoflo tees with a 2 pipe system because they have a separate supply and return pipe instead of just 1 main pipe for both supply and return from rads. Should have auto feeder but not necessary and has nothing to do with your problems as long as there is sufficient water in system.

The boiler is not cycling because the emitters are using more heat faster than the boiler can make it. Changing pipe size will only do more harm. All factors not taken into consideration when figuring boiler replacement. Your new boiler is most likely a lot smaller than the old one with a lot less water but the rads still use the same amount btu's to heat so with maybe 10 gals of hot water in the boiler at 145*, the rads are sucking the heat out of the water so by the time it reaches all the rads it's cooled off so much that the boiler most likely will never cycle.

The boiler is doing what it is suppose to be doing. Turn your boiler up to 180 so your rads will heat up better and your water should come back warmer but it may never cycle. Your concern should be your boiler cracking if it's cast iron from the difference between the hot going out and the cold returning to the hot cast iron boiler possibly causing cracking. You should have a bypass from thr supply to the return to temper the water.

 
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Old 12-11-22, 02:37 PM
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As far as the expansion i belive #30 4.5 gal tank surfice. Has a 2 gal tank now but i like that suggest of a by pass. When i corre t the air scoop i may run a 0.5 copper line [supply side] to the cir-pumptside raise the temp of the inlet wayer. As gar as the mono flo stayed just didn't want any confusion. The whole issue the boiler will not reach temp. N just a fyi this is not a condenstate boiler. Thks. I believe Will dig out sum of my old documentation pretaining to flow rates n btu loss. Thks again. I do like imjecting hot mdischarge into the return. Simplelest suggestion. Won't hv to jack threads.
 
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Old 12-11-22, 10:04 PM
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The system bypass you are discussing hot supply to cold return is not what you want to do. Years ago it was correct, but that changed with smaller boilers and less water volume.
The idea is to reduce the flow in the boiler and let it get hotter faster.
With that being said it is best to use a boiler bypass. This is cool return to hot supply using a full-size pipe, maybe 1-1/4". You will also have to have at least one valve between the bypass and the boiler either on the supply or return.
Here is a link for drawing and better explanation.
Bypass Piping
 
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