Exhaust Draft Inducer Question

Exhaust Draft Inducer Question

PostBy: vermontday On: Fri Mar 21, 2014 7:18 pm

I am adding features to my Logo boiler controller and have the following question; which do you think is the best way to control exhaust draft inducer fans, wire them to come on at any time, just come on when there is a stoker call or just come on when the stoker is not running.

I currently have it programmed to come on at settable time intervals for settable on times to minimize coal usage. While it is currently programmed to pull on the draft inducer strictly on time, regardless of stoker run or not, I can easily change the program to not come on if the stoker is running.

I don't have a draft inducer on my boiler, but if I needed one, I would think that overcoming the lack of draft in the summertime would be most important between stoker runs to keep the fire alive.

Appreciate your input.

Thanks
vermontday
 
Stoker Coal Boiler: EFM 520

Re: Exhaust Draft Inducer Question

PostBy: Keepaeyeonit On: Fri Mar 21, 2014 7:53 pm

Vermontday ,first off I have to commend you on your setup :up: very nice. If I were to do something like that I would look into Dwyer photohelic model A3000 Its a manometer/switch combo so I think you could wire it to run your inducer to come on say at .02"WC and off at .04"WC or what ever fits your needs(check first before you run out and get one, there not too expensive but new its over $300.00) to make sure it will do what you want. Keepaeyeonit
http://www.dwyer-inst.com/Product/Press ... 3000/Specs
Keepaeyeonit
 
Hand Fed Coal Stove: Hitzer 983 insert
Coal Size/Type: Mammoth nut
Other Heating: oil furnace,and a crappy heat pump

Re: Exhaust Draft Inducer Question

PostBy: vermontday On: Fri Mar 21, 2014 8:21 pm

keepaeyeonit,

A Dwyer Photohelic would be ideal. I have used many of these at work. I think your answer is the best way to go. It would automate when you needed draft assistance.

The Logo is programmed to take an input to turn on the draft circuit. That input can be a Photohelic measuring duct negative or an outside temperature switch to only come on during hot weather or simply a manual switch the you switch on when the weather is iffy.

I could put a small time delay in that would allow the Photohelic not to pull on the draft inducer during wind gust disturbances.

The only negative with a Photohelic is the cost, as you mentioned. If people wanted to just use the Logo alone off a switch as a start, they could replace the manual switch with a Photohelic in the future.

I will add the small time delay. It will work with any of the inputs.

Thanks

Do you think a draft inducer would be of help when the stoker first fires to prevent smoke or do you think that the pressure of the combustion blower would take care of it?
vermontday
 
Stoker Coal Boiler: EFM 520

Visit Lehigh Anthracite

Re: Exhaust Draft Inducer Question

PostBy: Keepaeyeonit On: Fri Mar 21, 2014 8:50 pm

I can't answer that(I have no stoker experience at all) but in my opinion anyways I think as long as you have a decent draft I think it wouldn't be a problem,are you having a problem with smoke now?
Keepaeyeonit
 
Hand Fed Coal Stove: Hitzer 983 insert
Coal Size/Type: Mammoth nut
Other Heating: oil furnace,and a crappy heat pump

Re: Exhaust Draft Inducer Question

PostBy: Carbon12 On: Fri Mar 21, 2014 8:52 pm

Is that meter sensitive enough for draft purposes?
Carbon12
 
Stoker Coal Boiler: Keystoker KA-6
Coal Size/Type: Rice/Anthracite
Other Heating: Heat Pump/Forced Hot Air Oil Furnace

Re: Exhaust Draft Inducer Question

PostBy: vermontday On: Fri Mar 21, 2014 9:07 pm

Good question.

The Dwyer 3000 Photohelic can be ordered with different ranges. The A3000-00AV claims a range from 0 to .25" w.c.

It would be scraping the bottom of the range, but might do it.
vermontday
 
Stoker Coal Boiler: EFM 520

Re: Exhaust Draft Inducer Question

PostBy: lsayre On: Fri Mar 21, 2014 9:41 pm

There is one of the requisite 0"-0.25" models on eBay right now for $95 with free shipping. It is claimed to be new. Thats about 1/3 of the going price.
lsayre
 
Stoker Coal Boiler: AHS S130 Coal Gun
Coal Size/Type: Stockton Anthracite Pea
Other Heating: Resistance Boiler (13 KW)

Re: Exhaust Draft Inducer Question

PostBy: vermontday On: Fri Mar 21, 2014 10:14 pm

No, I have never had a problem with smoke. I have had outfires on hot summer days.

I am just adding features to the program. People can select which features they need for their situation.

That is a good price on a Photohelic if it goes for that.
vermontday
 
Stoker Coal Boiler: EFM 520

Re: Exhaust Draft Inducer Question

PostBy: Keepaeyeonit On: Fri Mar 21, 2014 10:46 pm

I think the Photohelic is sensitive enough, It uses a light sensor on each set point to read the needle of the what really is a magnehelic gauge I have one and I can tell you first hand Its real sensitive. The one problem I see is if it triggers the inducer say at .02"WC and it stays at .02 or just under the upper set point then It will run nonstop until it reaches it set point and If It won't reach that point It will never stop so I think a timer somewhere in the circuit is a necessity(so it won't run continuously) but I think you should call and talk to someone about it.
Keepaeyeonit
 
Hand Fed Coal Stove: Hitzer 983 insert
Coal Size/Type: Mammoth nut
Other Heating: oil furnace,and a crappy heat pump

Re: Exhaust Draft Inducer Question

PostBy: vermontday On: Sat Mar 22, 2014 5:16 am

The Logo will cycle it via the user set draft on interval and user set draft off interval. I currently have it set for 20 minutes on and 20 minutes off.

The on interval time also pulls in a holding contact around the input signal for the on interval time.

This prevents the draft inducer from short cycling itself should a negative pressure switch be used as the input (the draft inducer might immediately satisfy the low negative setpoint otherwise).
vermontday
 
Stoker Coal Boiler: EFM 520

Visit Lehigh Anthracite