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Alpine Burnham ALP210B Soft Lockout

jduda Member Posts: 3
I have an Alpine Burnham ALP210B that was installed in my house in 2014. Last year I had a house remodel which involved the conversion of 1/4 of my house from radiators to radiant heat. The remainder of the house is still using radiators.

After the radiant heat was installed I have an occasional problem where I will get a Soft Lockout with Code 14. This code points to Delta T Inlet/Outlet High. Temperature rise between supply and return is too high.

The radiant heat addition resulted in the addition of 1 additional zone pump. The radiant heat also added a temperature reduction to lower the temperature for the radiant heat from 180 degrees to 135 degrees. The reduction mechanism returns water directly to the return loop. I have 3 zones. 1 zone for radiators, 1 zone for radiant heat, and a 3rd zone for domestic hot water using an indirect hot water storage tank.

When the soft lockout occurs, I have to power cycle the unit. It doesn't seem to want to come back on line on its own. It's been stuck like that for hours at a time (overnight). When I power cycle the unit, the unit starts right up and seems normal again.

This problem appears to only happen when its abnormally cold outside. Like 0 degrees F or lower. It doesn't happen all that often.

I downloaded and reviewed the I&O Manual from U.S. Boiler Company.

I am wondering if my problem is caused by the return pump not being powerful enough after the addition of the radiant heat. The I&O manual recommends a Taco 1400-45 pump. This pump has specs of 1/3 HP, 150 PSI, 3450 rpm, 55 GPM. The pump that was installed back in 2014 is a TACO 0011-F4. This pump has specs of 1/8 HP, 125 PSI, 3250 RPM, 31 GPM.

I also have an external temperature sensor. The sensor is mounted on the house on the North side. The location is well protected. This sensor appears to be working normally.

Does this theory of needed a stronger return pump seem plausible? Would it explain why the problem seems to only occur at low temperatures? I assume the probability of all 3 zones being on at the same time for longer periods of time might align with lower temperatures.

Any advice appreciated.



  • DZoro
    DZoro Member Posts: 1,048
    More than likely something is wrong with how it is plumbed, and yes probably the choice of pumps and locations of them. Some pictures of the entire system would be of great help.
  • jduda
    jduda Member Posts: 3

  • jduda
    jduda Member Posts: 3
    I posted some pictures to show location of the return recirculating pump.