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Phil, Mechanical Engineer
Category: HVAC
Satisfied Customers: 8511
Experience:  Retired HVAC/ Electrical & Boiler contractor. Industrial
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Rick. I have an EK1 with an old Rodgers 1145-42. My blower

Customer Question

Customer: Hi Rick. I have an EK1 with an old white Rodgers 1145-42. My blower does not work in 'auto' mode so I was looking for a fan limit switch. The WR doesn't look like it, so I checked the voltage coming to the blower from the standard 2000 control board, It only puts out about 15-26 volts from the a1 connection where it hooks up. It appears that the blower looks like it needs 25 volts. So, where should I, a humble home owner, start looking?
JA: Thanks. Can you give me any more details about your issue?
Customer: The blower works from all other settings- heat/manual, AC/manual, and AC/auto which all seem to provide 25 volts to the blower. But, the Heat/auto setting only provides 15 volts. Where do I look?
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Submitted: 1 year ago.
Category: HVAC
Expert:  Rick replied 1 year ago.

I'm going to open this backup to my colleagues so one of them can help. Please don't respond (even to acknowledge this post)until you get a response from us. If you respond first it will only delay your answer.

Expert:  Phil replied 1 year ago.

Hello,. there are close to a million of these type products on the market, I need the full brand name and model number to identify it... a verbal description will help as well, so far I don't know if its a furnace, a boiler or a toaster.

Next please attach a well focused, close up photo of the wiring diagram glued inside the service panel, the picture needs to be taken from straight on, in very good light.

You can use the paper clip- icon at the right end of the tool bar at the top of this dialog box to attach it here.,Include a picture of the thermostat wire connections to the printed circuit board in the same area.

If you have an error code showing, tell me what the code read out is on the wiring diagram or a sticker next to the diagram please.

If there is no paper clip-icon, look for the '+attach files' link at left of your send button.

I can mark it up with trouble shooting instructions.

We can go from there.

Customer: replied 1 year ago.
Ok- I will get what I can. give me five or ten mins.
Customer: replied 1 year ago.
OK, as expected, no wiring diagram anywhere. Here are pictures to give you a general sense of what it looks like. It is a boiler that heats up about a 50/50 mix of water and approved antifreeze. The left side of the control is two leads from the thermostat on T2 and A1, two leads from a 25v transformer on A1 and A2, a single lead for the blower on A2. You can see the jumper between T2 and A2. I suspect the problem to be here since the son (who lives here) says there was a loose wire and it was reconnected to where he thought it should go. No way of knowing which and where. What do you think?
Expert:  Phil replied 1 year ago.

The blower needs 120 volts, but from here without a wiring diagram trouble shooting that will be next to impossible.

We can however look a few things over.

Tell me if the boiler water pump is running or not... if it is running... then look for air bleed valves at the high points in the system, there will be one near the top of every radiator... send me a few photo's of those.

There is a flow switch in the system, that will not let the boiler fire unless there is water flow, if there is any air trapped in the system, that will prevent water flow.

Let me know what you find, we can go from there.

Customer: replied 1 year ago.
The boiler heats well, and the pipes are hot. The hot water goes thru coils which the blower blows over - no radiators. The 25 volts appears to be a signal voltage to the blower (which as you say runs on 120v). All the signals (AC or Heat manual, and AC auto are 25v where I measure them. With 25v, the blower goes on. I just don't know where the 25v is supposed to come from for the Heat/auto. There is a air bleeder just above the control board (oddly) and when I activated it, almost no air came out, just liquid.
Customer: replied 1 year ago.
Rick, I guess what I am asking is how the blower is activated without a fan limit switch?
Customer: replied 1 year ago.
Rick, I need to leave where I am and run to the house. My phone is(###) ###-####and my email is***@******.***. I know this is a tough one without a wiring diagram, but I was hoping your contacts might have one for the system 2000 control board. Since it is Christmas eve, if you don't get back to me before next week, that is ok. Just call or email. Have a good holiday and I will catch you when you are ready.
Expert:  Phil replied 1 year ago.

Hello again,

The blower on a boiler is activated by a timer in the control module.

Typically on a call for heat the signal starts the hot water circulating pump, then if the hot water flow switch closes, power is sent to the exhaust blower, then if the *pressure switch closes indicating a vacuum in the combustion chamber, the ignition is energized and the gas valve is energized...

beyond that, if the flame sensor fails to detect flame within 5 seconds of the gas valve opening, the gas valve is de-energized, and ignition is attempted 3 more times, if after 3 tries the flame sensor does not detect flame, the boiler goes into lock out mode.

*in the absence of a pressure switch, there is a flue damper motor with an end switch it that must close before ignition can occur.

The company does quality control on our work, with direct contact by telephone or email they want an additional charge, to cover that added expense. Its an option... I will submit that additional service as an option ....if you accept you have my private email and can email me directly. If you do not accept the charge, just post back in this dialog box.


I work here on my own time and expense, and am only paid if you rate my work.

We are on the honor system here. Please remember to rate my service before you leave today. It is how I earn a living, and does not increase your charges.

If you need anything else, just let me know. You can continue asking follow-up questions at no additional cost.

Customer: replied 1 year ago.
I guess I did not provide enough info. This EK1 System 2000 is an oil burning boiler that is working fine, including circulation pumps, etc., but whatever mechanism turns on the fan/blower that moves air through the ductwork does not work. The fan/blower works when it is activated by the thermostat in AC/manual, AC/auto, or Heat/manual, but not in Heat/manual. The thermostat works fine by calling for AC or Heat, and turning on the fan/blower to run continuously (manual) or to run with the AC in auto. But if I call for Heat, the boiler cranks up as it should. If the fan/blower is on manual, it comes on as well and run continuously no matter the temperature. But, If I call for Heat, and the fan/blower setting is 'auto', I get boiler and hot pipes but no fan/blower. The lead that shows 25v and turns on the blower/fan will only show 15v near the blower/fan and only shows 15v coming off the system 2000 A1 lead. Either that lead is supposed to show 25v and is damaged, Since I only know about a boiler using a fan limit switch to control the fan/blower, I am in unknown territory. If you can answer that question, we are good, otherwise a phone call won't help.
Customer: replied 1 year ago.
I won't rate you until you think we are done. Please let me know.
Expert:  Phil replied 1 year ago.

Thanks, ***** ***** coil should have its own wiring diagram, remove the access door over the blower, the diagram should be inside, attach a close up, well lit, well focused picture of it here,

The fan is either on a time delay relay of about 60 seconds or a fan limit control as you suspect.