Old Gravity Feed Boiler Water Temperatures

[lono]

I've lurked on the Hearth/Solar sections of this forum and found the information to be very helpful, but may have blundered into a problem with my own conventional system that you guys might help extricate myself from.

My house in central CT has an early 30's oil fired gravity fed boiler (fmr coal) which for the most part, performs fairly well. We really like the iron radiators!

However, on a recent kitchen remodeling - on the advice of our plumber we had the 2 under cabinet iron radiators replaced with hot water kick heaters. Unfortunately, these heaters don't seem to "kick in" ie the blower motors won't engage until the water temps hit 130-140 F. The plumber said that it was probably because the boiler water temps were so low due to the recent warm spell we were experiencing. However we recently had 2 consecutive mornings in the high 20's and with the thermo set to 68 F the furnace ran for the better part of 2 days w/o triggering the kick heater blowers. I used an infrared gauge that I use for tire/rotor temps on the track and the steel pipes leading into the toe kick feeds were indicating 110 after running the furnace for about 6 hrs (outside temp 45 - inside 75).

I guess my question is: what water temperature should I expect from a pipe that is roughly 20-30 feet away from a typical gravity fed boiler of that era?

Sorry for the long post, thanks

 

[Redox]

The coil in a kickspace heater isn't going to work in a gravity system. It needs a circulator pump.

Chris

 

[lono]

Thanks, just got a message from the furnace man confirming this. Not enough circulation.

 

[Chris S]

ALso, if you are using ODR and experiencing lower boiler temperatures, consider changing the control on your kick heater to a low temperature one. Beacon Morris offers this as an option. As stated above however- it won't work in your situation
Chris

 

[lono]

ALso, if you are using ODR and experiencing lower boiler temperatures, consider changing the control on your kick heater to a low temperature one. Beacon Morris offers this as an option. As stated above however- it won't work in your situation
Chris

A friend who advises local not for profit renovations of older pre-war housing suggested installing a 2nd pump assisted zone to feed the kick heaters. Presumably plumbed with similar gauge copper piping. Sound's a little esoteric and potentially incompatible with the old boiler. The alternative - gasp - electric.

Scott

 

[heaterman]

I've lurked on the Hearth/Solar sections of this forum and found the information to be very helpful, but may have blundered into a problem with my own conventional system that you guys might help extricate myself from.

My house in central CT has an early 30's oil fired gravity fed boiler (fmr coal) which for the most part, performs fairly well. We really like the iron radiators!

However, on a recent kitchen remodeling - on the advice of our plumber we had the 2 under cabinet iron radiators replaced with hot water kick heaters. Unfortunately, these heaters don't seem to "kick in" ie the blower motors won't engage until the water temps hit 130-140 F. The plumber said that it was probably because the boiler water temps were so low due to the recent warm spell we were experiencing. However we recently had 2 consecutive mornings in the high 20's and with the thermo set to 68 F the furnace ran for the better part of 2 days w/o triggering the kick heater blowers. I used an infrared gauge that I use for tire/rotor temps on the track and the steel pipes leading into the toe kick feeds were indicating 110 after running the furnace for about 6 hrs (outside temp 45 - inside 75).

I guess my question is: what water temperature should I expect from a pipe that is roughly 20-30 feet away from a typical gravity fed boiler of that era?

Sorry for the long post, thanks

That's sad. Those will never work with a gravity system unless you add forced circulation to them............which in turn will likely screw up the rest of the gravity system.
Was this guy a real live heating mechanic or just a plumber that solders pipes? There's an ocean of difference between a plumber and a heating mechanic. Two different fields with the only commonality being water in pipes.

Just for giggles, take your infrared and check the temp of your radiators and piping as compared to the toekick after the boiler has run for an hour.

Even if you would install a lower temp thermostat on the toekick you still wouldn't have enough flow through the smaller pipes to keep the fan running. Water is basically lazy. It chooses the path of least resistance and right now those big old gravity pipes and rads offer a lot less than the little 1/2" tube in those toekicks.

 

[lono]

I've lurked on the Hearth/Solar sections of this forum and found the information to be very helpful, but may have blundered into a problem with my own conventional system that you guys might help extricate myself from.

My house in central CT has an early 30's oil fired gravity fed boiler (fmr coal) which for the most part, performs fairly well. We really like the iron radiators!

However, on a recent kitchen remodeling - on the advice of our plumber we had the 2 under cabinet iron radiators replaced with hot water kick heaters. Unfortunately, these heaters don't seem to "kick in" ie the blower motors won't engage until the water temps hit 130-140 F. The plumber said that it was probably because the boiler water temps were so low due to the recent warm spell we were experiencing. However we recently had 2 consecutive mornings in the high 20's and with the thermo set to 68 F the furnace ran for the better part of 2 days w/o triggering the kick heater blowers. I used an infrared gauge that I use for tire/rotor temps on the track and the steel pipes leading into the toe kick feeds were indicating 110 after running the furnace for about 6 hrs (outside temp 45 - inside 75).

I guess my question is: what water temperature should I expect from a pipe that is roughly 20-30 feet away from a typical gravity fed boiler of that era?

Sorry for the long post, thanks

That's sad. Those will never work with a gravity system unless you add forced circulation to them............which in turn will likely screw up the rest of the gravity system.
Was this guy a real live heating mechanic or just a plumber that solders pipes? There's an ocean of difference between a plumber and a heating mechanic. Two different fields with the only commonality being water in pipes.

Just for giggles, take your infrared and check the temp of your radiators and piping as compared to the toekick after the boiler has run for an hour.

Even if you would install a lower temp thermostat on the toekick you still wouldn't have enough flow through the smaller pipes to keep the fan running. Water is basically lazy. It chooses the path of least resistance and right now those big old gravity pipes and rads offer a lot less than the little 1/2" tube in those toekicks.

The plumber is supposedly a heating specialist - probably not conversant in these "classic" systems, I would guess. I agree, it seems a little risky to introduce an independent pump-circulated zone into the system given its age/configuration.

Now to reverse the plumbing & the billing. Thanks for your advice.

Scott

 

[EForest]

If those old under cab rads are still around then put them back and all is well. If not then ask the plumber his thoughts on re-piping the two heaters off the bottom of your boiler as a separate zone with a taco 007 pump. The rest of the house should not be effected if properly piped. I've worked on many older homes with hydronic heating systems that incorporated gravity and pump, steam and pump, baseboard and air, and once i worked on a house that had a steam boiler with cast iron rads, a baseboard zone, radiant slab, and a warm air coil off the bottom of the boiler! It's all in the way the system is piped.