Some questions about fittings and placement...

warno

I'm currently installing 750 gallons of water storage that will be heated with my outdoor boiler via a plate heat exchanger. I'm going to use a heat dump zone if the boiler starts getting to hot and I'm using air scoops to try to keep the intrailed air in the lines from going to far. My questions...

I know heat dump zones are typically natural draw up to the dump zone so in the event of a power outage they still work, but on my boiler there's a draft door that will shut killing the fire in that situation so I'm not concerned. On my heat dump zone I plan to run it in line with my boiler side of the heat exchanger. I'm thinking about using a circulator to push the water from my hx line up to the heat dump water coil. I was thinking about using a large tee fitting to tie my heat dump circ to before sending it up to the coil. My thought is that would allow the water flow to slow down some so the 2 circulators on that line wouldn't fight each other. Is this necessary? My lines are 1" I'm thinking the tee fitting would be 2". I'll attach a rough drawing.

My other question I think I know the answer to but I'll ask since I'm still very new to this. Air scoops go in before the circulators, correct?

Any help or input of any kind would be great.

warno

Rough drawing

Ironman

That's not gonna work. You've got the circs in series; they need to be in parallel with checks on each one.

warno

Would a N/C zone valve be better on the dump zone supply? Wired to have it open when the boiler is getting to hot. Will that work?

Ironman

A normally open on the dump zone and n/c on the HX. 'Normal" means with no action or power applied to it. A normally open valve would open during a power failure.

warno

I only need it to open when the dump zone is needed. In a power failure the boiler has its own shut down to prevent runaway. Also when the dump zone is active I would still like the water to run through the hx to help scavenge heat from the boiler.

warno

I suppose it could work either way in my case. How hard on power are the zone valves to hold closed? I will need a 110 volt one since that is what my temp controller is.

warno

http://www.supplyhouse.com/Taco-Z100C2-1-1-Zone-Sentry-Valve-Sweat

Would this valve be ok? I know is 24v, but what's another $15 transformer.

Ironman

warno said:

http://www.supplyhouse.com/Taco-Z100C2-1-1-Zone-Sentry-Valve-Sweat



Would this valve be ok? I know is 24v, but what's another $15 transformer.

Sure.

warno

I'm not trying to say your wrong with what you told me I'm just trying to tell you what my system has and I'm asking for help. I sometimes come across as a smart a$$ through text but I really am just asking for help.

warno

Can anyone help me out? I'm just trying to get it done right the first time.

Ironman

I'm not sure what further info you're looking for. 2 zone valves with one circulator would work.

hot_rod

I wonder with that much storage that you need a dump zone? If so, a single pump and common 3 way zone valve should work. What kind of flow rate?

warno

Ironman, I thought your "sure" answer to my valve option was really short like I had offended you or something.

I was wondering why I should shut down the flow to the HX all together? Shouldn't that line remain open to help scavenge heat if possible?

Alittle more info on the my heat dump location. My boiler is located outside my garage in its shed. I only have one set of lines in the ground and the shed isn't big enough for fin tube style heat dump over head. So my heat dump has to go in my garage. Plus that will be heat for the garage if it's dumping. So I didn't think a natural flow would happen having to go under ground 3 feet Then back up into the garage, Then up the garage wall to the rafters another 8 feet.

The only reason I'm wanting a heat dump zone is if my boiler is running and my storage is close to temp. Possibly in the warmer days where I miss judged how much wood to load in the boiler.

I'm hoping to get at least 6 gpm to my HX. But it's not plumbed yet, I still need to figure out how many elbows I'm running through to get a more accurate number on the flow.


So would the better option be to shut down the hx flow and flow only to the heat dump zone? Is the thinking that if storage is up to temp it wouldn't scavenge heat anyway? I'm just trying to understand is all.

hot_rod

Heat dump indicates to me that all the system and storage is already constipated and the "dump" is a last resort to prevent over-heating and damage or relief valve lifting.

Personally, with your system I feel it is overkill.

Suppose you run your tank to 180 or 185.
The load becomes satisfied, buffer is fully charged, boiler still full of wood.

Air fan shuts down, boiler starts to ramp output down.

With that much volume, I suspect you could handle all the "load" in the boiler by over-charging the buffer to 190 or 195 possibly, if this is a rare expected occurrence, and your boiler has fast responding control ?

Another option, that would follow your logic is to dump excess into a non critical zone, like a basement, or garage, anyplace but waste to the outdoors would be a better use of that energy.

I think dump zones are sometimes considered as a protection for a failure mode. Like the boiler draft or fan does not shut down, or a natural draft type boiler in a power outage, where the boiler keeps running full fire after the load drops.

I guess it depends on how much protection and $$ you want to spend on protection from the arbitrary.

Ironman

warno said:

Ironman, I thought your "sure" answer to my valve option was really short like I had offended you or something.

You inferred all that from that one word?

I'm not offended in any way with you.

Since we don't know what make of ODWB you have, we don't know what's needed as far as storage, dump zone, etc.

I agree with hot rod that you may not even need a dump zone. Most major ODWB manufacturers like Heatmor, Central Boiler, etc. have all the necessary controls and buffer built in where you don't need a heat dump. As long as air is completely shut off to the fire by a limit control, it doesn't really matter how much wood is loaded.

Now, if you have a wood boiler where the fire is regulated by a thermal draft control, then yes, a dump zone would be prudent. Especially if its a pressurized vessel.

warno

I often fear I come across badly through text online when asking for help. I'm not a very articulate man so I tend to think that way when I'm reading my own posts or other's replying back to me.

My boiler is a homemade non gasifier. I'm trying to get it to achieve secondary flame with modifications to the firebox. I think this winter I will have that happening. But anyway I don't know the btu output of my boiler for that reason.

I won't have much money incorporated this heat dump zone. I have the fan and I'll build the water coil at work so the only money I'll have is in the plumbing up to it. It may never get used but I figured alittle added insurance is better then a boil over situation.

So basically a simply 3 way zone valve on the hx loop to the heat dump will be good? Should I run it normally open to the dump zone? Which valve would you guys recommend?

Thank you for all the help.

hot_rod

We would need to know how many GPM you will be running to get you the correct valve.

Commonly sourced zone valves are typically 1/2 - 1-1/4" with a Cv of 7-8.

We sell a lot of these valves for solar and hydronic diverting valves.

It has a 7.5 Cv, so 7.5 GPM at 1 psi pressure drop. It would be workable up to maybe 10 gpm without too much pressure drop.

If you want to move larger flow rates you might look at Belimo or one of the other commercial type manufacturers.

As for NC or NO, if you chose a spring return style, use the valve in the most common position with no power consumption. So only power the valve when you need to dump.

This valve doesn't have a NO/ NC choice, just flip the body or switch the piping to change from a NO or NC configuration.

warno

Ok I'll figure up the flow rate tonight and report back. Thank you.

hot_rod

with a home made boiler, ideal flow rate will be a trial and error. How many BTUs/ hr are you aiming for?
Maybe size a pump to the heat load at design and build the fire, watch the ∆T across the boiler and work from there.

With 1" connections I'd guess you want 80- 100,000 BTU/ hr?

If so and you run 20° ∆T, then a 1" ZV should be a workable size.

warno

Looks like I should be able to get 6 gpm to the heat exchanger pretty easy.

I've tried to guess my output of my boiler with online calculators but I don't think it was accurate. I know last year when I ran my garage loop alone I was seeing delta T of 12°F with the fan running on my system. This year with the storage I will have to refigure everything. I'm hoping my boiler is in the ball park of 100,000 btu.

warno

Ok so I'm going with the Z300637 valve body and the z126000 actuator. Does that sound right? Thanks for all the help guys.