Block Heater Thermostatically Controlled

[bostonhatteras]

"Positive snap-action switch" = Mechanical, requires no power to operate.

Interesting design. it must vary the pressure on the bimetallic strip. I always think of snap action switches being for one temp setting only. For exhaust over temp and such

 

[Boatnut]

Interesting design. it must vary the pressure on the bimetallic strip. I always think of snap action switches being for one temp setting only. For exhaust over temp and such

The term snap action refers to how the contact mechanism works internally in the switch. It is a positive way using sort of a cam action, it helps insure the switch is securely in one position or the other.


I don't know how many heaters are in the various engines, but FWIW you can get contactors with multiple poles. It is typically best to switch both hot legs if you are using 220 volts. If you want to use only one thermostat, you could get a large multiple pole contactor and use one contactor to control the heaters in both engines. (Note, these contactors can be quite costly). I have installed several block heating systems in the past. We have always used 2 contactors, one for each engine, controlled by a single thermostat. A power switch is installed the the line side of the thermostat, and a switch in the load side to each contactor. Switches set up this way allow the system to be totally turned on and off with one switch, or to allow turning one only one set of engine heaters on or off should one fail and require maintenance. Also there are solid state contactors that are sealed units, with no worries from sparks from the contacts. Using standard contactors, I like to put them in a box because of the possible contact arcing.

Hope this helps, good luck.

 

[JLR]

It helps a lot. In fact, the installation was completed yesterday. We used two contactors because I was uncomfortable only breaking one of the two 110v lines for each block heater. So, two OEM toggles to manually turn on and off the block heaters. Two contactors (in boxes) to break each 110V hot leg for each block heater with two thermostats to turn the block heaters on and off with the thermostat including two new indicator lights to reflect when the thermostats are closed.

 

[JLR]

Now that the thermostat project is done, I am on the hunt for that internet or cell phone activated 220v relay so I can turn on the block heaters remotely. I neither need nor want one with a thermostat- just the relay. Any ideas?

 

[Boatnut]

Now that the thermostat project is done, I am on the hunt for that internet or cell phone activated 220v relay so I can turn on the block heaters remotely. I neither need nor want one with a thermostat- just the relay. Any ideas?

There is no such thing as a relay to connect to a cell phone or computer. You have already installed the relays you need to turn the heaters on, what you need is a laptop, a software program, and a interface to do what you want. The computer through the interface will turn on the relays you have already installed. I am think Cruiseair sells a unit that can do what you want for a/c, you could possibly adapt it for the heaters.

If you aren't willing to spend a few bucks, I doubt you will be interested in doing this

 

[Boatsb]

Systems are available to trigger the relays from amx or crestron. They also allow touchscreens on the boat to control them and other things. It's not cheap but it will do what you want easily and reliably.

 

[JLR]

Still looking for a wifi 220V switch. Price aside, I just can't seem to find what I am looking for.

 

[drburke]

I think your best bet, as Scott mentioned earlier, is to consider home automation.

Most have some network access capability, but generally assume you have internet access to your boat; is this the case? Do you have an always-on wireless router?

First, visit http://www.smarthome.com I recommend you stay within the Insteon line due to its widespread use.

You could buy a starter kit (for the controller aspect) making sure it is network accessible and has an associated phone app, usually having one or more control modules. You would additionally need the 220V module separately.

Or, you could buy only the controller and module you need. One example would be an Insteon hub #2242-222 and an Insteon 220/240V 30A normally open controller #2477SA1 priced at $129 and $119 respectively.

http://www.smarthome.com/2242-222/INSTEON-Hub/p.aspx
http://www.smarthome.com/2477SA1/IN...ntroller-Normally-Open-Relay-Dual-Band/p.aspx

Once the system is up and running, you will likely find *many* other uses for additional modules and remote sensing.

DAN

 

[JLR]

Dan - thanks for the help. I do have a network devoted to my boat. I am also told to ask whether the relays or switches I will be getting, while normally open, are of the " latching" kind. In other words, when the relay completes the circuit, it will need to stay closed until I decide when to turn it off(open it).

 

[JLR]

Also, in looking at the specs, which appear to my lay eyes to be perfect for my application, I am just a little confused on one aspect. Does the hub communicate with the switch by RF or by some other means. The distance between the hub which gets connected to the router by an Ethernet cable is easy but the distance between the hub and the switch will be down two floors. I am not sure an RF signal would pass through. Also, if it is using the boat's electrical wiring to communicate with the switch, I am not sure if that would work on the boat. Assuming these are not issues of concern, it looks perfect to me.

 

[Genesis]

I have a significant number of things operating off dry contacts here at the house (pool/spa gear, HVAC, etc.)

I would look into the RLY8XA box along with the ADICON RS-485 interface. You'd have to build the code for it (I did) but it is dead-balls reliable, has a programmable timeout if comms is lost (so if the computer goes insane the relays drop out) and just plain works. I've had the system here running for a decade without a single problem and I had the same system running in my former house from when I bought it to when I sold it. It also runs on 12V power so it's convenient in that regard. The RLY8XA is not a power-relay box but it certainly can drive one; that's how I use it for the pool gear; it drives a pair of 30A power relays to provide two-speed pool motor control and a handful of dry contact closures to switch valve positions and command the heater.

It's not really an off-the-shelf solution though as it requires some sort of intelligence to drive it.

I have not seen a "quick, reasonably-cheap and easy" solution commercially available for this -- IMHO there's a market for it, but I've yet to find it. The obvious reason someone would build it in the line-voltage world in a house is to put an electric water heater on automation.

 

[drburke]

Just to follow up, Karl's approach is a little more hands-on and low level, but does offer some brute-force reliability. (It is an X-10 device, which is an alternate home automation protocol.)

The items I mentioned are not latching, rather they expect the condition set in the hub to maintain its state with the exception of a power outage.

The communication on the Insteon product is billed as "dual band", which in this context means it communicates redundantly both via piggyback signals on the power line(s) as well as low power RF. The RF is sufficient for home use, which is a farther range that you expect, generally.

DAN

 

[Genesis]

Well, you CAN use the RLY8XA on X10 if you insist, but I don't. X10 is unreliable enough (and has no polling function to confirm operation) that I instead run these modules on the ADICON RS-485 hard-wire interface. Being RS-485 it's differential and extremely reliable. The only issue I've had with it in over 10 years of use was a somewhat-recent electrical storm that featured a lightning hit about 50' from the enclosure out the back door -- that managed to scramble the addressing on one of the modules and required its re-initialization. I have two of these modules (one a SECUI16 ADC module for pool/spa temperatures and similar, front-ended by a home-built OpAmp conditioning board) and a RLY8XA in a sprinkler-controller cabinet outdoors; easily as harsh an environment as a marine one (given that I live on the water) and I've had no trouble with either.

What I'd love to find is something that runs on Z-Wave, which is bidirectional (and thus can be very reliable as you can poll endpoints), mesh-based (so it will continue to operate properly, albeit a bit more slowly, if one or more endpoints fails for some reason) and open protocol. Unfortunately Z-Wave hasn't taken off as I hoped it would (my software supports that as well, and it works fabulously) and as a result the obvious sort of controllers that would work for this application (either water heater or a sprinkler controller that you could use as a driver for power relays) are anywhere between difficult and impossible to find.

 

[JLR]

Just as I was ready to pull the trigger on the Insteon setup, my research reveals that there appear to be too many complaints regarding manufacturing defects in the module designed to trigger the relay. So, I am looking for another solution among the home automation products. I am also trying to figure out whether Karl's suggestion is something that I can do myself.