Central Vac Alternative: Is is up to code?

The central vac in a property we are working on failed. It "needs new."
Are there any "code" issues with wiring in one of those packaged
transformer/relay gadgets used for furnace control. The 24 volt thermostat connect would just go to the contacts on the host "ports" in the house. The relay would switch the AC going to an outslet for a central vac. I would put switch loop for "local control" of the vac.
I figure the relay transformer would essentially last forever. I could burn out several "shop vacs" for price of one packaged "central vac."
Anyway, is that anything "wrong" with switching an outside like this?
EMWTK
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As long as the packaged relay control unit is installed per the manufacturer's instructions there should be no code issues with the installation. However, assuming that you are planning to use this to switch the outlet that the central vacuum was plugged into could be a problem as the contacts of most furnace controls are not rated for the 15 to 20 amps that could be plugged in.
A second issue is the actual performance of a shop vacuum when connected to the extended piping of the central vacuum system. The central units I have installed were all rated for a significantly higher pressure drop then any shop vacuum I have seen in use. Thus, while this "rube goldburg" will work, its performance will probably not be acceptable.
Finally, what is wrong with the curent central unit? If it is just a motor or controller failure these are available on line, typically for less than the cost of a good shop vac ($125). I would rather check into repairing the current system and avoid all of the compromises of the proposed alternative.
Dave PE Master Electrician
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I haven't made any final decisions yet. I did connect a shop vac (turned it one and off by walking down into the basement) and it seems to have more power than the old unit which was about 30 years old. The BIG negative is that "shop vacs" (especially in the large sizes) make a lot of noise. One of the great advantages of the central is that the only noise you hear is the slight "woosh" of the air going through the hose but motor noise isn't much of an issue unless we were actually in the basement--then it was almost as loud as a shop vac and conversation was impossible when it was on. I can hear the shop vac through the entire town house.
I'll make do with that for a week or so and do some checking but the last time I looked central vacs were a little more than what you saw.
The relay/transformer I saw (Home Depot) definitely was rated 20 amps with 40 amps locked rotor. The circuit the old vac was on was just 15 amps and the vac itself had a build in CB which "tripped" without tripping the CB in the panel. (The only other load on the circuit was/is a "piggy back" transformer for the doorbell.)
Maybe I can find some working X-10 stuff for the short term to reduce the number of trips to the basement.
Thanks for letting me know that there isn't a problem with switching the outlet.
ine, typically for

I don't know about "good" but you can definitely get pretty powerful shop vacs for well under $100.

Thanks, again, for your advice.

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