Re: Air con circulating pump

Brent Cameron

It’s not hard to find relays that can be energized by 240VAC signals and that can switch 24VDC devices. You just want to be sure that the switching capacity isn’t exceeded (eg trying to use a 10Amp relay to control a 20Amp motor).  You also need to understand if the circuit is normally open or normally closed (or the relay is energized to close contacts to start/run the motor or vis versa). My guess would be Normally Open which also means the relay can be depowered when not needed and will use no power when the motor isn’t running).   You also want to be sure that the relay can handle the start currents of the motor as they can be considerably higher than the run current.   


On Oct 7, 2021, 1:41 PM -0400, Scott SV Tengah <Scott.nguyen@...>, wrote:

The engineers in the group or a marine electrician (ha!) will have to give their opinion, but I think all you need a relay that has a coil that is capable of handling 240vac. The relay would be controlled by the 240vac signal that normally would power the pump, but rather than powering the pump, it energizes the relay and connects 24vdc from the batteries to power your 24vdc pump.


You’ll have to check, but I presume a relay that can handle 240v in its coil can also handle 24v. Just make sure the contact current capacity is enough for your pump.  


The 240v is AC and the 24v is DC, but I’m not sure that makes a difference.


From: "" <> on behalf of "Nicolas Klene via" <laixoi@...>
Reply-To: "" <>
Date: Thursday, October 7, 2021 at 4:29 PM
To: "" <>
Subject: Re: [AmelYachtOwners] Air con circulating pump


Hi Stefan


I am installing the same pump as you  with that “box” as a 220v/24v transformer which I find flimsy! 

If Scott can tell us a way to connect it to the 24v with a relay , I would be very interested !!

Thanks in advance Scott .


SV DarNico

Amel 53 #471

Le 7 oct. 2021 à 15:04, Stefan Schaufert <mail@...> a écrit :

Dear Scott,

would it be no problem switching the 24V DC with 240V AC by a relay?
I am not sure about that, but I decided against this idea.
Some research in the web told me, even a solid state relay (usually only available for AC-AC if you need it for 240V to 24V)) only switch it on, but not off again, even if I did not understand that ;-(.
But I am not an electric engineer and have to believe what I find for this issue.
What would your solution look like for that?

Best regards
A54 #119 Lady Charlyette, currently La Palma - Canaries

Nicolas Klene
SM2K # 471
In Marseille

2007 A54 #69
SV Tengah

Brent Cameron

Future Amel Owner & Amel Owner Registry Moderator

Oro-Medonte, Ontario, Canada

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