I have carrier air and heat heating on on heat unit but it has two it has two 28 volt relays that operate the heat strips. One was not working so I purchased another onewith the same ratings but it won't energize. They both say 28 volt dc but when I measured it it has 28volt ac on them. The only thing I can fiqure id their must be a rectifier in the old one. Did they make one like this and where do I find one or can I add a rectifier to the new one. Hope there is an answer out there Thanks.:

Exact model number?

Carrier 50zp-402-311 This uses two relays to control the heat coils. The heat coils were made by Warren Tech Model wzp1002

Carrier 50zp-402-311 This uses two relays to control the heat coils. The heat coils were made by Warren Tech Model wzp1002

Info for you Carrier dropped Warren in 2001

http://www.docs.hvacpartners.com/idc/groups/chanpart/documents/bulletin/111-01-73.pdf

Warren heater web site to contact them

Warren Products - Heaters (http://www.warrenhvac.com/common/products/cbk.html)

Now if you have the exact relay numbers I might be able to transpose them. All the numbers and brand name are needed for the relays to be able to do this..

Here is also a PDF of there products.

http://www.warrenhvac.com/info/cbkcatalog06.pdf

The contacts might be rated at 28 VDC. There my be an AC rating too. I suspect that the coil is 24 VAC. Need relay part numbers.

The Relay is a AE4138 24011wf
30a-240vac
20amp 28volt dc hope this helps

I have just about all major catalogues for HVAC components and there is no cross over for that Number.

What part of the world do you live in? Are you in the USA?

Some of the foreign catalogues I do not have . If all else fails contact the manufacturer.
Sorry but no help on my end.

I live in Florida and purchased the unit in 2000 new thanks for trying

Is there a brand on the relays. You can always move them and substitute. Sometimes there are icons that identify a brand. Can you take a pic and post via "Go advanced"?

A HUGE selection of relays can be found at Relay Specialties, Inc. - A World of Components (http://www.relayspec.com)

Coil and contact rating must be known.

This is the contact rating:

30a-240vac
20amp 28volt dc

US - Electronic Components Distributor | Newark.com (http://www.newark.com) and Digi-Key Corporation - USA Home Page (http://www.digikey.com) have selector guides.

If this is off board, then it's a simple contactor and readily available.

These are better relays. SC-E1-24VAC Products (http://web5.automationdirect.com/adc/Shopping/Catalog/Motor_Controls/Fuji_Contactors_-z-_Overloads/32_to_50_Amp/SC-E1-24VAC)