Not good but great relays

Big Will

I have a chiller that we put together a year ago. It is residential application so it needed to be small and quite. So I used the chiller builder kit by standard refrigeration. This allows the use of a Trane condenser = quiet. I had to use a few control relays. Think DPDT 24 volt and 120 volt coil. To start the pump and condenser. We have had three problems with it so far. The first was a broken control wire. The second was a bad freeze stat and the third was a failed relay. The wire was an easy fix. The controls was replaced by a JCI aqua stat. Now the relay. The customer is getting pissed. So i apologized and told him I would replace the three control relays with the best on the market. Witch begs the question. Who makes a great relay. I regularly use Mars and Honeywell. I can't say I have had problems with them. However there is always a company who stands out with any product. So opinions anyone?  

Techman

Relays

What kind of problem are you having w/ the relays?Are the amp ratings being overamped?Is the 24v @ 24v?.  I've used both H.W. and Mars w/ no problems.R.I.B. also has a good relay.but watch the amp load.Don't forget the  motor starting amps can be 4-6 times the normal running amps !

Big Will

No amp draw

The relay that failed was used for control voltage only. Of the three relays the only one with a load is running a small Grundfoss pump.  I agree about the lack of problems also. I do carry both honeywell and mars relays and they do fail but at a reasonable rate after a reasonable time.

Mike Kusiak_2

Relay failure

How did the relay fail? Did the coil open or did the contacts develop high resistance?



Using a power relay to switch low current control voltages can sometimes lead to problems. Oxide can build up over time on the contact surfaces. The contacts are usually designed to self clean when switching higher currents, but fail do do so with low voltage and current signals. 

Big Will

open coil

But what you are saying makes sense. I think I am going to look at the IDEC ice cube relays.

Mike Kusiak_2

IDEC relays

I have been using IDEC relays in electronic and control applications for more than 20 years. They have been very reliable, even when abused with higher than rated voltages applied to the coil.