Burnham boiler

[Bail]

Hi, I have a mid century house here in California with radiant heat floor it’s about 1400sqft. My question is I have the boiling water temperature set to 250°, but the gauge never seems to get past 120° the pipes supplying feel hot to the touch in return feels warm. I am wondering why after three or four hours running constantly the temperature never goes above 120° I know one problem may be the expansion tank is about 20 years old. I’m wondering if anyone knows about a good thermostat that would act more like a timer cycling it on and off thanks for the help.

 

[DanInNaperville]

You may have two heat sources. Radiant heat is typically limited to about 120 degrees or less - you wouldn't want to walk across a floor that warm or warmer...
It's a bit of a problem, since cast iron boilers have limited life spans is they're run for long periods of time at less than 140 degrees
Burnham/US Boiler cast iron boilers are rated to run with 110 degree return water for limited time periods, but have to warm up to more than that to avoid excessive condensation that can cause corrosion.
Older in-floor radiant heat was typically designed to run on higher temperatures with radiant heat loops spaced pretty far apart and buried pretty low in the slab. If your house was built in the 1960s to the 1980s, that could be your situation. Those installations would run water at higher temperatures that dissipated across the slab before reaching the feet of the occupants.
If you have access to a thermal camera, you can view the layout of the in slab tubing when the heat is one and has been running for 10 minutes or so. Modern installations are often about a foot between lines while older installations would be 3 or 4 feet.
Regardless, a good first step would be to replace the thermometer (may be a combination thermometer/pressure gauge) to be sure that's not the issue.
The boiler shouldn't let the temperature setting to be higher than 180 or 190. Even if there's a number on a dial that goes that high, the high temperature limit (a separate control) is usually fixed at 190 on those boilers.
Does the house get as warm as you need it to?

 

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[Fitter30]

You don't have a modern radiate heat system with copper tubing in a cement pad. The major problem is that the lime in the cement eats holes in the copper and the only fix after about 20-25 years. Now when i worked these systems it was early 1970s in st. louis. In California you must have a different makeup of cement. Cast boiler like you have minimum return water temp 135-140° for two reasons condensing inside the burner chamber to the flue the other is cast boilers don't like a cool / cold return temp that will crack a section of the cast iron. The gauge shows temp and pressure is called a triacator. Take couple of more pics of the boiler and piping. 50 year old gauge i know its bad.

 

[DanInNaperville]

One other thing that you can look for is a thermostatic mixing valve - it could look something like this: https://www.supplyhouse.com/Caleffi...ion-MixingCal-3-Way-Thermostatic-Mixing-Valve It's designed to limit the temperature of the water going into the slab and/or going into the boiler (depending on how it was set up). Like the valve in your shower, it's designed to maintain a constant temperature when water temperature and flow changes. It could be that your boiler is hot but most of the water going into your slab is being recirculated instead of coming from the boiler.

 

[John Gayewski]

Your boiler can't be set to run at 220 degrees. Not sure what problem your having.

 

[Bgard]

You don't have a modern radiate heat system with copper tubing in a cement pad. The major problem is that the lime in the cement eats holes in the copper and the only fix after about 20-25 years. Now when i worked these systems it was early 1970s in st. louis. In California you must have a different makeup of cement. Cast boiler like you have minimum return water temp 135-140° for two reasons condensing inside the burner chamber to the flue the other is cast boilers don't like a cool / cold return temp that will crack a section of the cast iron. The gauge shows temp and pressure is called a triacator. Take couple of more pics of the boiler and piping. 50 year old gauge i know its bad.

Lime is a base material, it has a Ph of~7 it does not eat copper! Holes in the copper tubing would most likely be caused by someone strapping the tubing to steel reinforcing wire mesh or rebar, my house is 75 years old with 4000 sq ft of copper tube radiant heat, never had any issues. The OP probably has a primary secondary system with a mixing valve installed to prevent the water in the floor to get above 120*, depending on the flooring material I wouldn’t recommend going higher than 130*

 

[Fitter30]

Lime is a base material, it has a Ph of~7 it does not eat copper! Holes in the copper tubing would most likely be caused by someone strapping the tubing to steel reinforcing wire mesh or rebar, my house is 75 years old with 4000 sq ft of copper tube radiant heat, never had any issues. The OP probably has a primary secondary system with a mixing valve installed to prevent the water in the floor to get above 120*, depending on the flooring material I wouldn’t recommend going higher than 130*

Though it from lime was wrong but these houses were built in the 1950's and 60's
According to the Portland Cement Association the interaction of copper with both dry and wet concrete should not cause a corrosion concern. However, copper should be protected when it comes in contact with concrete mixtures that contain components high in sulfur, such as cinders and fly-ash, which can create an acid that is highly corrosive to most metals including copper.
unfurl="true"]https://copper.org/a...rner/problem_e thebedding_copper_concrete.php

 

[Fitter30]

Though it from lime was wrong but
According to the Portland Cement Association the interaction of copper with both dry and wet concrete should not cause a corrosion concern. However, copper should be protected when it comes in contact with concrete mixtures that contain components high in sulfur, such as cinders and fly-ash, which can create an acid that is highly corrosive to most metals including copper.

Plumbing: TechCorner - Is There A Problem With Embedding Copper Tube In Concrete?

It is completely acceptable to bury/embed both hard drawn and annealed copper water tube in concrete. Decades of satisfactory service experience with the use of copper tube for in-floor radiant heating systems, water distribution systems and snow melting systems attest to the compatibility of...

copper.org