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Re: Flue condensation after boiler replacement
Per the manual, the return temp should not get below 130F. I'm guessing you need numerous changes here. Consider installing a bypass using a globe valve to throttle it so you can temper the return water. I'd put the circulator on the supply so you're pumping away. You need to provide the delta T, combustion analysis including stack draft, circulator rating in GPM, and your aquastat settings. Your stack temp is way too low to generate natural draft. This unit comes with a 15 second post-purge, which is way too short. You could install a delay on break timer to get at least 2-4 minutes pp. If you have an ODR, you'll need to contact the mfr. for advice per the manual.
The chimney should be lined and properly sized. They claim this unit is CAT I and CAT III but with the oversized flue, long vent connector with offsets (unsupported) and needs a draft inducer. They rate it 84% AFUE even though most sources consider 83% the max to still be considered CAT I. Yours is effectively a CAT II.
Combustion analysis will show if it is being underfired, which would contribute to the problem.
A barometric damper would add dilution air, stabilize the draft and reduce condensation.
Re: Flue condensation after boiler replacement
It does lower the stack temp when open, which is due to high draft conditions. It reduces condensation just like a draft hood, which is the same as opening a window or door when showering. You reduce the Rh%. A fan assisted furnace does not have dilution air.
I have a thermostatic bypass valve on my boiler as Hot Rod suggested and it works great to maintain return temps and prevent thermal shock. I put a globe valve in the bypass so I can throttle it as needed. Ball valves are isolation valves and horrible for throttling. Gate valves are a little better, but their Cv is still worse (higher) than a cheap globe. This means you could get erosion from cavitation and require a larger valve for a given flow/ pressure profile.
Re: Sq ft of steam:sq ft of EDR
So, is the 996 sq ft rating on the 64-08 actually 749 sq ft when you take out the pickup factor?
My EDR is 332 sq ft, but a radiator was removed at some point by a previous owner that I would like to reinstall. This will likely take the system to 360 sq ft. Would the Peerless 63-04L rated at 383 sq ft be ok? My current boiler is rated at 479 sq ft.
Paul posted an excellent chart for the Peerless 64 above.
Take a look at "gross output" for the 64-08. You will see 318 for steam. This is the output after the combustion efficiency is included in the data. You lose 81 KBTU out the chimney.
Now look at the "net ratings" for steam. You will see 239. The manufacturer assumes that you will need 33% additional capacity so they rate the boiler at only 239 KBTU despite the fact that its output is actually 318. The 33% reduction has been a bone of contention around here for years.
If it were me, I'd use the 63-03. 98 KBTU yields 408 sq ft. You'd have a pickup factor of 48 sq.ft (360 EDR)…………..12%. Plenty if you insulate the piping and install it per the manual. It will never cycle on pressure.
LRCCBJ
Re: Sq ft of steam:sq ft of EDR
Every boiler manufacturer's STEAM EDR/SQFT spec includes the 33%.
If it says it's good for 300SQFT, that includes the 33%. If you want to go by the book, if you have 300sqft, you find a boiler that says 300sqft.
ChrisJ
Re: Pilot light goes out in the middle of the night **SOLVED!**
The chimney will have more draft when it is warm especially after a long cycle but assuming it has a draft hood that is supposed to isolate the appliance's draft from the vent's draft. It does have a draft hood and not a barometric damper, right? Even with a draft hood there can be enough draft to pull through the appliance in some cases. Is the thermocouple centered in and well enveloped by the pilot flame?
mattmia2
Re: Pilot light goes out in the middle of the night **SOLVED!**
Did you check the supply pressure?
mattmia2
Re: Best option for two thermostat C-Wire placement on dual-zoned boiler [Crown AWR Aruba]
It sounds like you have a grasp on the situation. Your common wire connection sounds correct. I believe that you can use the same Class 2 dry contact thermostat on both the DHW and the CH leads. Crown boilers are very user friendly in most cases. Also their Tech Support is top notch.
Re: Asking for advice for combi boiler replacement and hydronic system upgrades
Your drawing (which I put below) does indeed have primary secondary piping and is a proven piping strategy, though I would consider locating the expansion tank on the suction side of the primary loop pump
GGross
Re: Pilot light goes out in the middle of the night **SOLVED!**
Yes, that boiler has a draft hood built-in.
Re: Asking for advice for combi boiler replacement and hydronic system upgrades
see page 57/58 in the manual, they REQUIRE primary secondary. I wouldn’t stray from the manual.
hilltown