Adding automatic vent damper to old cast iron boiler?

bnjmn

Have a customer who wants to increase efficiency of existing cast iron residential boiler. Boiler is late 70s vintage but still in great shape. Are there any products or kits out there to add a vent damper to this boiler to decrease standby losses? Never ran into a situation like this, boiler is in great shape with lots of life left in it.

icesailor

Vent dampers:

I don't know if anyone makes the anymore. In the late 70's, early 80's, they were popular. I installed one on every oil boiler I installed. The same one worked on gas. They were problematic and every one was eventually wired or blocked open.

Technically, I think that if it isn't OEM, you're not supposed to retrofit them. Of course, anyone can do whatever they want.

Tim McElwain

Field Controls

offers the GVD, which used to be an Effikal damper now owned by Field. They are an authorized retrofit. The expected added efficiency is about 3 to 4 %. If the boiler has a pilot make sure the plug is removed from the damper blade. See www.fieldcontrolsw.com/gvd/.php

Tim McElwain

Correction to Field

Controls site for GVD damper www.fieldcontrols.com/gvd.php

JeffM

GVD on EZ-Gas

Can a vent damper like this be used on a Carlin EZ-Gas retrofit? I see how the thermostat calls the damper to open and then the switch in the damper enables the gas burner after fully opening the damper. But how would it handle the post-burn purge time of the EZ-Gas, which is about 30 seconds?

John_88

adding automatic vent damper to old cast iron boiler?

I read the install manual of the damper and it didn't say you couldn't install it in your application.



But to be sure and to CYA



I would contact them



FIELD CONTROLS, LLC



t: 252.522.3031





Email: sales@fieldcontrols.com

Tim McElwain

ANSI Z21.8 does not allow

vent dampers to be used with conversion burners.

Tim McElwain

Actually the original vent dampers

back in the early 70's were all retrofits. Honeywell, Johnson, Flair and Effikal all were originally promoted as a retrofit. The utility I worked for installed many of them during that time.



The only problem today may be the fuse that is included in designed systems that blows on the first call for heat. This is so if the damper is disconnected from the primary control the system will not work. The blown fuse is not replaceable by the way. That is the safety.

JeffM

thanks

Thanks, Tim. I knew you'd have the answer! Not was I was hoping to hear, but at least now I can stop thinking about it.

SWEI

What would be the point?

If the burner is not running, how much air will actually go up the stack?

JeffM

the swinging damper

The air I'd like to stop from going up the stack isn't coming through the burner, but entering at the double-swing barometric damper. I've got a 35 ft. interior chimney which has a strong draft and keeps the damper pulled open all of the time, so the basement heat loss is quite high.

Tim McElwain

You could install

another barometric or a neutral pressure point adjuster (flue restrictor). I have the specs for such a device.

SWEI

Can you seal up the basement?

That might reduce the inflow to a reasonable rate.  ROI is typically very attractive on this type of work.

JeffM

hard to seal

I have done a considerable amount of air sealing in the basement, but can't get it to modern standards. House was built in 1890 and the foundation is random sizes of granite block, so stone work has lots of tiny leaks and air can come down through the floors a little too. Basement was warmer when I burned oil as the single swing damper closed more fully when burner was off.

Slimpickins

Don't waste your money

You will never recover the money you spend putting in an auto vent damper on a boiler that age. In my neck of the woods it would cost the customer $XXX to $XXXX to have it installed by a HVAC contractor. Have the customer save their money and invest in a new mod con rather than invest their hard earned money on a 30 plus year old boiler.

Steamhead

So what advice would you give

if this was a steam boiler?

Slimpickins

No advice

I can't give advice on steam boilers because they're really rare where I'm at but I'm interested in your opinion.