New York Boiler- Minimum Temp?

Cyclist77

I came across a CG40 and the specs say that it can have a minimum return temp of 130F. This is a cast iron boiler.

Am I missing something here?

BTW, where do New York boilers land on the quality scale?

EBEBRATT-Ed

I think New Yorker is made by Burnham which I am not a fan of but many like them.

All CI boilers are 130 min return water temp.

techforlife

They are trying to avoid corrosion from flue gas condensation. For high mass systems, primary/secondary (injection) piping would be desired.

hot_rod

the 4 way valve you have discussed, is another option to protect a cast boiler.

Cyclist77

I understand the 4 way mixing valve. It was the 130F return temperature that is confusing me as I thought it needed 135F to avoid condensing.

jesmed1

As long as your flue gas temperature is 350+ degrees, your boiler is not going to be condensing regardless of the return water temp. It may condense briefly on startup from cold, but after a few minutes when the exchanger gets hot and your flue gas temp is 350+, any startup condensation is gone.

The other reason for the 130 minimum is to avoid thermal shock from cold return water cracking the cast iron, but I have two Weil McLain WGO-5's that have been running (on oil) for 30+ years from cold start sub-130 return water temps and no mixing valve or bypass, with no ill effects, and no condensation.

So while I would install a bypass or mixing valve per mfr's installation instructions, or pipe primary/secondary as suggested, the dangers of low return water temps in cast iron boilers have been exaggerated, IMHO.

hot_rod

All boilers condense on a cold start condition. As does your ICE powered vehicle.
You want to limit the amount of time that a non condensing boiler operates below the fuels dew point. 130 is a realistic number to use for gas, oil and lp.
The industry rule of thumb is within 10 minutes the boiler and entire flue warms above dew point.

The distribution piping and heat emitters drive the operating temperature of the boiler. High mass concrete slabs , some gravity conversions are systems watch for with non condensing boilers.

Primary secondary piping does not necessarily prevent low returns to the boiler, nor will a hydraulic separator, or a 4 way mix valve

There needs to be a temperature sensor involved to respond and adjust flow rates. Some intelligence added to the piping.

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https://www.caleffi.com/sites/default/files/media/external-file/Idronics_23_NA_Heat%20transfer%20in%20hydronic%20systems.pdf