Safety Valve for Coil

Safety Valve for Coil

PostBy: traderfjp On: Tue Feb 19, 2008 2:52 am

I 'm installing a coil into my coal stove. I'm using a storage tank and a Taco pump. I wanted to know what would happen if the pump failed? Is there any safety device I can install that would still let the water circulate in the event of a pump failure? I PRV everywhere but I don't want the coil to bake without any water in it.

Thanks in advance
Stove/Furnace Make: Alaska
Stove/Furnace Model: Channing 3

Re: Safety Valve for Coil

PostBy: stokerstove On: Sun Feb 24, 2008 1:27 pm

Interesting question, wish I had a concrete answer. I've been thinking about the same thing. My coil and Grundfos pump have been in service for at least 5 years with no failures other than power outages. I have the PRV's where they belong and they work well.
I am planning to buy a replacement pump for next season and keep this one for a spare - don't know how long they last - mine runs constantly all season.
For the power outages I have a small gen. to run the stove, pump, and some lights. I used to use an inverter but the pump would be too much for it.
I'm sure there is a way around this problem such as a circut that shuts the stove down if the pump fails (that is if you are running a stoker) or possibly a couple of selenoid valves that would bypass the pump if it failed.
Hopefully someone has done something similar or has a better idea.
Hot Air Coal Stoker Stove: Alaska Kodiak Stokerstove 1

Re: Safety Valve for Coil

PostBy: Dallas On: Sun Feb 24, 2008 1:40 pm

I believe, the fluid will flow through the pumps via natural means, even though the pumps aren't running. Remove the power from the pump and see if the heat isn't traveling up the pipe. Of course, if the pipe takes a turn "downward" the flow will stop. Hot water will naturally rise.
Hand Fed Coal Stove: Modified Russo C-35
Other Heating: Oil Hot Air
Stove/Furnace Make: Russo
Stove/Furnace Model: Modified C-35

Re: Safety Valve for Coil

PostBy: LsFarm On: Sun Feb 24, 2008 2:36 pm

Dallas is correct, the water will flow through the pumps at a reduced rate if they are not running, Unless the pump has a flow control valve in it designed to stop 'gravity flow'.

If the PRV is located after the coil, and the cold water supply [well or water system] is before the coil, if the PRV opens, to vent a steam buildup in the coil, then the pressure of the water will force water through the pipes and the coil till the PRV has cooled off and closes.. So if the water stagnates in the coil, and boils, then the PRV will open, then close, again and again, the frequency will depend on the heat in the stove,and the temperature of the water in the piping. This is one very good reason to put a pipe, elbow and long 'drip leg' on the PRV and put a bucket under the drip leg. The steam and hot water will be caught in the bucket, and you can see what is going on, istead of water all over the floor.

Most circuits will thermosiphon some once they have been 'started' with a pump, but they will be pretty slow with the flow restrictions created by lots of elbow, the pump, etc.

As for using an inverter to run a pump. the small cartridge pumps only pull a little less than an amp.. the taco 007 is 1/25 hp, and pulls .78 amps.. virtually any inverter will handle this.. Unless you are using one of the 'oldfashioned' B&G model 100 pumps with the 1/3hp motor, they eat electricity and maintenance time and parts.. the cartidge pumps will run 24/7 for a decade or more,, I have several doing just that. The B&G pumps were a constant source of work and maintenance in my previous homes and heat systems.

Greg L
Stoker Coal Boiler: Axeman Anderson 260
Hand Fed Coal Boiler: Self-built 'Big Bertha' SS Boiler
Baseburners & Antiques: Keystone 11, Art Garland

Re: Safety Valve for Coil

PostBy: traderfjp On: Sun Feb 24, 2008 4:45 pm

I actually started this thread a day before my coil was up and running. I did confirm that the water will syphon without the pump turning. That is good news as Dallas pointed out.
Stove/Furnace Make: Alaska
Stove/Furnace Model: Channing 3