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28 amp Relay (replaces all relays, requires large transformer) Q&A

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AirVac AV425A Relay Replacement?

I have an M&S Systems Air Vac Model # AV425A. The problem is the motor runs continuously when the unit is plugged in. I can turn it on and off with the rocker switch. The motor continues to run when the hose is plugged into the wall unit and when turning the unit to off at the hose handle. Is this a relay problem. The unit has a separate transformer and relay. Can I get parts for this unit? Thanks! Lance

Answer:
Original parts are no longer available. It sounds like the tank's on/off switch is 110 volt, not low voltage, and acts like a kill switch. The relay is bad but all the electronics should be replaced with a new circuit board and low voltage on/off switch. An electrician will be able to handle all this easily using the simple connection diagram on the enlarged photo of the board. The hardest part is adding an additional hole, if needed to the tank for the board to pop through into two places. Here is what you need: https://builtinvacuum.com/retail/shopretail.php?part_no=235S,251

Relay Use With Larger Transformer

Why can't I use the smaller transformer with the 28 amp relay.

Answer:
Smaller transformers do not use enough electricity to operate the larger relay. The larger transformer suggested uses enough electricity to operate the vacuum.

External Relay?

I had a central vac with an external relay. It died so I hooked up the shop vac to my central vac pipes, and I turn it on manually. Are there external relays for sale? I have had no luck finding any.

Answer:
Sorry, no external relays available from MD MFG.

Replace Relay in Beam?

I have a Beam 297S that just keeps on running. Tried the on/off switch on the unit. Still runs. Pulled the low voltage wires. Same result. Only stops when unplugged. Will this Relay solve my problem?

Answer:
Did you pull the Low Voltage wires at the unit? You have to for the correct test. If it keeps running then you should use the first circuit board here to replace all the electronics. Your electrician can use the enlarged photo and be done in 1/2 hour. You save money and have one part that you know will work with the motor. This relay will most like not work because of its size and its the only one we sell. https://builtinvacuum.com/parts/electrical-parts.html

Latching Relay?

I have an old Filtex central vac, with a midtex(48-20q1a2) latching relay contactor, can I replace it with this one.

Answer:
If you have to start and stop your suction in the home by pressing something at or near the wall inlet then you have a true latching relay and those are not available any longer. You'd have to replace your vacuum unit and your wall plates. Takes some work but is totally possible. Call us for more help.

Relay or Board?

Replace relay? Or use modern circuit board?

Answer:
You can replace it with the circuit board by yourself by following the wiring locations on the larger photo of the product here
https://builtinvacuum.com/retail/shopretail.php?part_no=235M You'll have to buy some 1/4" flag terminals, wire nuts and some wire in case you need to extend any wire. Most likely you will have to drill some holes and patch some old ones in the can. You'll still have some of the same work if you buy the relay and transformer. The instructions are within the text here https://builtinvacuum.com/retail/shopretail.php?part_no=242,232

Nutone Parts Needed

I have a NuTone CV353 that has started working intermittently. I popped the top off (two screws) and went to work with a voltmeter. It looks like the relay is bad. It's a self-contained unit that says Alco e47895 on the outside of the plastic box. Where can I find a replacement part? Thanks, John from Nederland, CO

Answer:
You can try Nutone's website, or save money and put in the #235S circuit board to replace all the electronics. Only takes a bit of retrofitting but if you look at the reviews, it is a very popular thing to do. Your electrician can do it in 15 minutes, most likely, and we provide the instructions online. Just click on the enlarged photo of the board and print it out.

Relay for Smart Vacuum?

Hello: I have a Smart Model 361 and I think the relay is going bad it it. Do you carry these and what would be the price? Thanks, Darrell

Answer:
Hi, we only have the #242 stand alone relay and the #235S relay and complete electronic board. These may work for you. Call us for more ideas.

V-16 Central Vacuum

I have a V-16 model central vacuum. The brushes for the motor need to be replaced but I can't locate them anywhere. Any suggestions on where to get some or a compatible model. Thank you, Karly, New York

Answer:
Sorry, we don't have a cross reference for that model, but you can open it and take a couple photos of the unit and we can tell you what we know about it.

Stays on When Hose Unplugged

I have a CV30 Broan that was installed in 1993. Problem, when you shut off the power swich on hose, unplug hose, unit keeps running. Swich on Vac unit is in off position. You have to unplug vac unit to shut off. Motor seems to work strong. Is this a rely? Transformer?

Answer:
Hi, reinsert the hose and pull out slowly. Sometimes that is all it needs. If it happens again quickly go to the unit and unplug the low voltage wires from the vacuum unit. If it stays on then your relay is bad. If it goes off then the low voltage wiring is faulty.

Motor Works When Banged

my central vac (nutone) stopped working. originally if I banged on the unit it would start and run until i unplugged the hose. eventually that wouldnt work. it now just clicks when I plug the power at the socket in. would you know if the motor is shot or how I could troubleshoot that.

Answer:
Hi, that shows that the motor is shot. Replace the motor using this chart here and you will be up and running https://builtinvacuum.com/help/nutone/motor.html.

Motor or Relay Bad?

I have an old Kenmore Central Vac #116.4052090. When the wall unit is opened the motor does not run and I get a buzzing sound from the motor relay. I have bench tested the motor and it runs strong. I isolated the buzzing sound to the motor relay using a mechanics stethoscope. The relay in question is FSP 701366. Checking your site and many others I find that relay is no longer available. Is your relay #242 an acceptable replacement for FSP 701366? Thank you Frank Batavia, IL

Answer:
Hi Frank, it may be your motor. Many times a bad motor will work after being fondled. Run it for 15 minutes and see if it stops. Or connect it back to the relay to see if it works now. If it is really your relay then take a look at the wiring photo on part #242 and make the decision based on that.

Relay Bad? Keeps Running

When I turn the switch off on the power wand the vaccuum keeps running. If I disconnect the hose from wall the vaccuum keeps running. Is it the relay in the power wand? Thanks, Dan

Answer:
Please use www.builtinvacuum.com/flowchrt.html to find the answer to this question and get back to us if you get stuck.

Replace Fasco Relay?

I have a Fasco model 852svdm central vac and put 110v to each motor and they ran good. The relay is sparking and needs replacement. Is the MD #242 relay a replacement?

Answer:
Hi, use the photograph links to see how it is wired and see if that wiring is compatible with the wiring on your relay. It may just work.

Replace GE Relay?

WE have an old Broan V-16 Central Vac unit that came with our house. We have determined that the relay needs to be replaced. The old relay is a General Electric relay # 3ARR4 BA32, 24 coil volts, 60 Hertz, contact rating 240 V. The bottom of the relay reads 18F.L.A. 55 L.R.A. Will the Honeywell 28 amp relay be able to replace this relay? Thanks. Eileen Wantagh, New York

Answer:
Hi Eileen, we are about the change the wiring diagram to be more helpful for the 242 relay so that questions like yours can be answered by website visitors themselves since we don't have a long list of compatible relays. Stay tuned and check back in a couple days. (Sept. 8, 2008)

vs. 16 amp Relay

what is the diffrence in this one and the 241 size of contact or?

Answer:
The connection sizes are the same, just on the sides, not top. The main difference is the amount of amps they carry.

Replace 30 amp Relay?

I have a vacumaid 325 will this work it says 30A on the old one thanks

Answer:
Yes, it can replace a 30 amp relay in central vacuums.

Bad Motor or Relay?

One of the motors is operating and the other is not. Could it be the relay or is it the motor? How do I know which it is? I have a Silent Master "S5" vacuum unit model # MD-108SM 220 volt.

Answer:
99% of the time, the motor is bad. Rarely will one pole of a relay go bad. Type in test relay to find related articles on our website. Also remember that motors expire after about 800 or so hours.