Relay Question

[GBDamo]

Any advice would be greatly appreciated.

I have a slightly atypical job that requires the following to both power a single immersion heater:-

1 - iBoost+ solar immersion heater. To run for the majority of the time.

2 - Programmed switched feed via a contactor fed from a 230V 13A FCU. Powers the immersion for roughly an hour every week for sterilization purposes.

The hot water in the tank is primarily heated via an indirect coil within the tank, the iBoost+ adds power from the solar array and the contactor is triggered weekly to raise the temperature over 65[sup]o[/sup]C to sterilize.

My concern is to avoid back feeding the iBoost when the the contactor switches on.

My plan is to use a 230V ~20A DPDT relay with the iBoost+ on pole 1 NC and then do away with the contactor and have the switched feed on pole 2 NO.

Any thoughts?

 

[Pat H]

A change over relay does seem the best idea.

 

[seltechpc]

A change over relay does seem the best idea.

AC/O relay is perfect for this job. Just need to be sure the contacts are break before make to ensure the iBoost is not getting a pulse of back feed when it operates.

 

[Pat H]

If the iBoost is vunerable (it may not be) then would a second cutout be advisable?
Triggered from the weekly timer?
Belt and braces I know

 

[GBDamo]

Thanks guys,

Not sure if we're all referring to the same thing by different names (Me confused) but here is what I intend to use.

62.32.8230.0010 | Finder DPDT Plug In Non-Latching Relay, 230V ac Coil | Finder - http://uk.rs-online.com/web/p/non-latching-relays/2928427/

Attached to DIN rail by

9203 | Relay Socket For Use With 62.32, 62.33 250V ac | Finder - http://uk.rs-online.com/web/p/relay-sockets/4008402/?origin=PSF_428009|acc RS says its rated at 10A but the manufacturers data sheet confirms it is actually 16A

Scroll down to see the drawing, I intend to wire the the iBoost+ plus to 1 and the FCU to 6. When the coil is energised it should automatically disconnect the iBoost+ and divert power to supply from the FCU. In doing so I believe this will fulfill the "Break before make" criteria set by Seltechpc?

 

[GBDamo]

If the iBoost is vunerable (it may not be) then would a second cutout be advisable?
Triggered from the weekly timer?
Belt and braces I know

I hear you, really i do but where does that logic stop? and more importantly where does the expense stop. If the component is correctly spec'ed and compliant you have to draw the line somewhere.

 

[1Justin]

FYI, I think the Immersun (which is now available again despite ceasing trading some time ago) has inbuilt timer to control it's second (or third) output as a boost. Would save faff. More expensive than IBoost mind.

 

[LeeH]

The one I have has a legionnaires cycle on it.

It holds the tank above 60 for 1hour a week if selected.

Cannot remember the dam name! I'll go into the garage after tea and look.

 

[LeeH]

Apollo GEM PV water heating solar immersion switch - http://www.apollosolarproducts.co.uk/

Legionella Control - http://www.apollosolarproducts.co.uk/about/Legionella_Control/

 

[solarsavings]

I thought the iboost had the anti legionella facility inbuilt.

 

[LeeH]

No, it just says manually boost.

The apollo gem is the way to go, fit the GEM, sell the iboost.

 

[solarsavings]

Programmable Timer: 2 x switches per day with seperate programmes for weekday/ weekends. Save summer / winter settings.

I would use that fuction.

 

[GBDamo]

Got it to function in the end with no back feed. As the sterilization cycle is currently switched via a contactor the swap over to the relay was not too much of a faff and if fitted as standard then an iBoost can be fitted with little or no effort at later date.

The Apollo Gem looks interesting and is not that differently priced but allows the customer to override the sterilization function, as it's too easy to change the parameter and forget to change it back, they cannot access this function at pressent.

thanks for all the help