Hi Will
Nando is correct if you intend to use them in a heat sink or in air. I have used them successfully for a couple of years and never had a single one burn out yet! The trick is to use them as water heaters as per the pic below.
You can also connect them in series for 24v as per the pic. Just add as many as you need
I no longer use this as a dump load as I now dump through the inverter to 240v ac water heaters with a solid state relay and Omron time delay. But I keep it as a stand by. I had a runaway one very stormy night , a fuse went on one of the turbines during a big gust and I was able to use this to shut it down. I don't like shorting out a turbine in full flight never mind a runaway ! by shorting it through the dump it slowed it right down and then stalled it and allowed me to replace the fuse. Maybe not the best way to do it but it worked.
On another occasion the relay I was using to dump stuck in the on position and completely discharged the battery bank, but it still didn't burn out any of the glow plugs and they had been on for hours.
One word of caution though be careful with your choice of glow plug there are a few that have a built in thermostat avoid these and you will be fine. Another problem is getting a matching thread tap they can be tricky to get. I used VW plugs which are 12mm Fine. (same as there wheel nuts!)
There is lots of ways to mount them in a manifold, I simply cut a length of inch box section and welded VW wheel nuts to the sides and a couple of pipe fittings to the ends. The manifold is just inserted on a pipe from a beer keg filled with water. I have on occasion seen the water almost boil in the keg
Its a Cheap dump load if you have the glow plugs! But more importantly it works
I hope this is of some help to you
Russell
