Pump size

[Redox]

I have done remedial engineering for a number of years on large commercial buildings and have run into lots of design errors in my day. Cooling airflow issues always stand out as particular problems, but heating water issues rarely come up unless you are having a problem making capacity. Assuming that the house has an adequate system already installed and you are only able to move half the design flow of the boiler, the temperature difference will be double, but the heat will still get through to the end of the pipe. A 40 degree delta isn't efficient, but neither is an oversized pump that erodes your fittings whenever the system is in operation.

A storage tank would be my first suggestion, but having an oversized multispeed pump should allow you to slow it down in mild weather and keep the erosion manageable. I would also suggest a Spirovent in the system to catch any "microbubbles". Since you seem to be pushing the limits of what a residential circulator can do, it might be time to look at a commercial circulator. These can be had with a 3 phase motor that can be run off a speed drive for infinitely variable flow and maintain excellent energy efficiency at reduced speeds. It isn't a cheap option, but might solve most of the problem.

Chris

 

[Huskurdu]

I'm debating whether to pay the local installer his astranomical quote to install my boiler with the pex that's too small with a warranty or to remove what I've done and throw away $1000 worth or pex, pvc and insulation. So, what size tubing should I have used and where would I get it? I don't see many options for tubing over 1" w/02 barrier anywhere. The one place I spoke to in California said that the 1-1/4" pex was twice as much as the 1" and didn't come with the 02 barrier and the tool was $950 to install it. Seemed a little extreme to me. Looks like no matter what I do I'll have to borrow a lot more money to finish the job. :-(

 

[heaterman]

Husker

If your load is actually 72,000 (the output of the boiler) and
If you do all you can in the garage and the house to reduce head (IE 1-1/4" with as few fittings as possible)

My gut feeling is that you'll be all right.

The main reason being that I have rarely seen any boiler firing 100% of the time at it's full output. This means of course that your actual load is less than the boiler is capable of. Have you ever noticed the boiler in your house firing continuously when it's really cold? I doubt it.

The caveat here is that the system flow in your house with all zones running is probably higher than the flow you are going to get from the Econburn loop. This will cause your boiler to fire even when the wood boiler is running unless you turn the aquastat way down and run the Econoburn at 190*.

It's not an ideal situation but I don't think you're in the category of digging it up .


Rules of thumb for copper sized piping

3/4" = 40,000 btu
1" = 80,000 btu
1-1/4" 140,000 btu
1-1/2" 250,000 btu

 

[in hot water]

Stick with the 1". I don't know how you calculated the design load. most, if not all heat load calcs have some fudge factor.

Years ago at the RPA we compared 6 different heat load programs, from radiant manufacturers, and noticed a 20% spread. All seemed to error on the high side.

Also your 72K load is on design day. How many days are you at design temperature? ASHRAE has a spec for showing how often a city is at or below design.

Worse case at design or below design you may slip a few degrees, the heat doesn't just go away. if you have some mass or radiant, it may flywheel through those days, also.

hr

 

[BrownianHeatingTech]

I'm debating whether to pay the local installer his astranomical quote to install my boiler with the pex that's too small with a warranty or to remove what I've done and throw away $1000 worth or pex, pvc and insulation. So, what size tubing should I have used and where would I get it? I don't see many options for tubing over 1" w/02 barrier anywhere. The one place I spoke to in California said that the 1-1/4" pex was twice as much as the 1" and didn't come with the 02 barrier and the tool was $950 to install it. Seemed a little extreme to me. Looks like no matter what I do I'll have to borrow a lot more money to finish the job. :-(

That's why I suggested putting the storage tank in the garage, instead of the house.

From the boiler to the tank, you need to transfer the full 150kbtuh.

From the tank to the house, you only need to transfer a max of 72kbtuh, according to your heat load. The 1" will do that, fine, since that's roughly half the flow of the full boiler output.

Joe

 

[Huskurdu]

Here is what I am going to do. I will let you know if it works out.
I am going to 'upsize' my primary loop and my gas boiler return line where the secondary loop comes into them. This should 'slightly' reduce the 'head' restriction.....or whatever you call it. I'm going to put in 1-1/2" copper in these spots only. I'll also have to put in the appropriate 1-1/2" valves to go along with that.
I'm going to us the Taco 009 pump 'probably' unless the guys at Econoburn tell me not to. It's reasonably prices on Ebay ~200.00 and it seems to be a popular pump that will do the job.
I'm going to reduce that size of the secondary loop as much as possible to also reduce the restriction as much as possible. I'm also going to mount the pump low in the garage and connect it the return pipe on the gas boiler as high as possible in the basement of the house. It's gonna be darn close. If it just can't keep up this winter then I'll have to dig it up and replace with 1-1/4" pex, but I'm betting on this working. I'll be spending a bit more on copper and related valves,etc...but I think it will pay off in the end.
I appreciate everyone's input and will appreciate any future input also.

 

[jpowell1979]

You need a Taco 0011 pump.

I have a Greenwood 100 with 180' of 1" pex and it works great with plenty to spare.

Here is the math. 1"PEX is .06' per foot of head loss.

238 x .06' = 14.2' pf head loss.

Because you have a closed loop there is no head loss for the elevation, just frictional losses. The Taco 0011 will flow 18GPM at 15' of head. (broken link removed to http://www.taco-hvac.com/uploads/FileLibrary/00CurveChart.pdf)

You can transfer heat at roughly 10,000 BTU per 1 GPM so this would put you right around the 150,000 BTU mark. I got mine of ebay for way less than the local supply store.

 

[Huskurdu]

You need a Taco 0011 pump.

I have a Greenwood 100 with 180' of 1" pex and it works great with plenty to spare.

Here is the math. 1"PEX is .06' per foot of head loss.

238 x .06' = 14.2' pf head loss.

Because you have a closed loop there is no head loss for the elevation, just frictional losses. The Taco 0011 will flow 18GPM at 15' of head. (broken link removed to http://www.taco-hvac.com/uploads/FileLibrary/00CurveChart.pdf)

You can transfer heat at roughly 10,000 BTU per 1 GPM so this would put you right around the 150,000 BTU mark. I got mine of ebay for way less than the local supply store.

I see it's got a much better flow than the 009. I'm pricing them now.

Does anyone know what I could use for a zone valve that will open when the power fails? I would like to use it on my Power-out loop that runs through a radiator. I'd like to put a thermostat on it to heat my garage, but if the power fails I'd like it to open so that it will gravity flow (or whatever you call it when the hot water rises and the cold runs back to the boiler).

 

[Huskurdu]

Sorry, just to be clear....the zone valve that I need needs to open when power goes out.

 

[pybyr]

Sorry, just to be clear....the zone valve that I need needs to open when power goes out.

Google automag + valve

then you will also need to make sure your dump load is installed so that it can circulate by gravity (which basically means it needs to be above the boiler), forget if you have mentioned that on here yet

 

[heaterman]

You need a Taco 0011 pump.

I have a Greenwood 100 with 180' of 1" pex and it works great with plenty to spare.

Here is the math. 1"PEX is .06' per foot of head loss.

238 x .06' = 14.2' pf head loss.

Because you have a closed loop there is no head loss for the elevation, just frictional losses. The Taco 0011 will flow 18GPM at 15' of head. (broken link removed to http://www.taco-hvac.com/uploads/FileLibrary/00CurveChart.pdf)

You can transfer heat at roughly 10,000 BTU per 1 GPM so this would put you right around the 150,000 BTU mark. I got mine of ebay for way less than the local supply store.

.06 ft of head at what GPM flow rate?

Here's a bit of knowledge on Hi velocity circs like the 009 and 0011 or Grundfos 26-99 etc.. Any circulator needs a certain amount of pressure on the inlet of the impeller. Typically, the higher the head on the outlet side, the higher the inlet pressure needed to avoid cavitation and what I call "fried pump syndrome".
On a sealed system such as Econoburn, this is not an issue because you have 12-15PSI static fill pressure with which to keep the suction side flooded.
Such is not the case with an OWB because they are an open non pressurized system. When you have a static pressure of only 2-3PSI available on a circ that needs 3-4, the circ will not live a long and happy life. I have crates full of high head circs that smoked because of tubing that was too small creating the need for a high head circ. Nearly all of them are from OWB installations that used in excess of 100' runs requiring more than 6 GPM.
It's always better to do it right the first time. The fact that 1" tube is what "everybody" sells and uses, plus being less expensive than 1-1/4", doesn't mean it's the right stuff to bury on your job. A 15-58 will use about 100 watts of electricity. A 0011 will soak up 250+. Both of them will do this forever. Add it up over 5 years. Now factor in replacing a $200 circ instead of a $75 model at least once during that time period ........

I better quit. I feel a rant coming on.

 

[Redox]

Easy there, H M. You can only do so much...

"Fried pump syndrome" can be avoided by checking the NPSH (net positive suction head) line on the pump curve. In most small circulators, it isn't a concern, but the larger they are, the worse the problem can be. I have seen degreed engineers screw this up so many times, I can't count. The problem is particularly acute with cooling tower loops (gravity application) where the pump is placed some distance horizontally away from the tower. Sometimes it is so bad that the pump will pull a vacuum and the cavitation is audible. Add a little crap in the strainer and these pumps end up eroding their impellers in short order. It happens all the time!

Chris

 

[heaterman]

Easy there, H M. You can only do so much...

"Fried pump syndrome" can be avoided by checking the NPSH (net positive suction head) line on the pump curve. In most small circulators, it isn't a concern, but the larger they are, the worse the problem can be. I have seen degreed engineers screw this up so many times, I can't count. The problem is particularly acute with cooling tower loops (gravity application) where the pump is placed some distance horizontally away from the tower. Sometimes it is so bad that the pump will pull a vacuum and the cavitation is audible. Add a little crap in the strainer and these pumps end up eroding their impellers in short order. It happens all the time!

Chris

On the subject of engineers. I had a booth at a local steam and old tractor show a couple weeks ago. A guy came past inquiring about the product and during the course of the conversation he revealed that he was a civil engineer. Long story short, he was looking at an OWB which as typical has the supply on the bottom and the return on the top. The unit was clearly marked as such. He was sharp enough to see that the hottest water was going to be at the top of the water jacket but then went on to say that he was going to pull his supply off the top and simply mount the circ lower on the pipe. I told him that the head would be the same as taking the supply out the bottom UNTIL the circ came on at which point he would have only the "head" over the actual tapping in the water jacket. He didn't get it and argued amiably with me for about 10 minutes before leaving. He'll find out if he does it.

 

[Redox]

"Arguing with an engineer is like wrestling with a greased pig; after a while, you will learn that the pig likes it" - unknown

Chris

 

[kabbott]

You need a Taco 0011 pump.

I have a Greenwood 100 with 180' of 1" pex and it works great with plenty to spare.

Here is the math. 1"PEX is .06' per foot of head loss.

238 x .06' = 14.2' pf head loss.

Because you have a closed loop there is no head loss for the elevation, just frictional losses. The Taco 0011 will flow 18GPM at 15' of head. (broken link removed to http://www.taco-hvac.com/uploads/FileLibrary/00CurveChart.pdf)

You can transfer heat at roughly 10,000 BTU per 1 GPM so this would put you right around the 150,000 BTU mark. I got mine of ebay for way less than the local supply store.

Hmmmm?
Just so where all on the same page here
This is a pressurized system?
He only needs to transfer 72kbtu's correct?
so lets say 7 GPM
At 7 GPM 1 inch pex has a drop of 3.2 psi or (3.2 x 2.31=7.39) 7.39 feet of head per 100 feet. 7.39 per 100 x 230 feet = 17 feet(7.39 x2.3=17).
17 feet of head, 009 ifc does about 6.5 gpm at 17 feet head non ifc slightly more.
If he can shorten the 1 inch to 180 feet or so round trip it seems doable to me.

Are the numbers way off base?Maybe I need to go back to the books.
Not trying to argue just trying to help the fellow out and learn.

 

[heaterman]

If it were mine, I'd buy a 15-58 Grunt and try it before I went to a Hi-V circ. I'll bet that he'll get enough flow to take care of the load even with the longish runs of 1". Remember that an engineers first priority is to cover his a$$. Being that engineers came up with the design program I use and also developed the pump curves and specs listed in the manuals............you get where I'm going?

 

[Nofossil]

Any engineer worth his salt keeps a safety factor hidden anywhere that he can. If it's overdesigned no one will ever know, and someone else will pay for it. If it's underdesigned, everyone will know and he'll pay for it.

That's why my personal challenge is to do this gasification / storage / solar thing as cheaply as possible. Cost has a way of exposing unnecessary overdesign.

 

[Huskurdu]

I'm all for cheaper, but do I have a 'second' on the 15-58 Grundfos? At $93 vs $200-$300 it has brightened my day. Also a max of 87 watts at the highest speed vs over 200 watts
I'm a moron.....we've established that..... lol Please get to the meat and potatoes will ya'!!?? I haven't bought a pump yet so I'm still very open-minded on this....let me know what everyone thinks. Besides the more you guys 'discuss' the more I learn. I'm funny that way.

 

[BrownianHeatingTech]

I'm all for cheaper, but do I have a 'second' on the 15-58 Grundfos? At $93 vs $200-$300 it has brightened my day. Also a max of 87 watts at the highest speed vs over 200 watts
I'm a moron.....we've established that..... lol Please get to the meat and potatoes will ya'!!?? I haven't bought a pump yet so I'm still very open-minded on this....let me know what everyone thinks. Besides the more you guys 'discuss' the more I learn. I'm funny that way.

The 15-58 would flow your house load. It won't flow the full output of the boiler.

You need to under-fire the boiler (not load it fully), and should talk to Econoburn directly about the best way to adjust your boiler to operate at a lower output.

Doing storage now would solve the issue the right way, up front. Of course, there is the cost issue on that.

A large dump zone (eventually, this can become your garage heating zone) would take care of things if you accidentally put too much wood in it. That's probably the best balance between cost-effectiveness and long-term reliability.

Joe

 

[Huskurdu]

I'm only expecting this pump to push the 72k (give or take) to the house. The balance of the output of the boiler will be pushed through a heat exchanger for the garage out the other side of the primary loop. This pump will not impact the heat flow in the garage (not directly anyway). As stated before why spend the extra money on the much larger pump if it's not needed. I found a 15-58 Grundfos on Ebay for about $60.00.....it seems worth the risk to me. Thanks for the input.

 

[heaterman]

I'm only expecting this pump to push the 72k (give or take) to the house. The balance of the output of the boiler will be pushed through a heat exchanger for the garage out the other side of the primary loop. This pump will not impact the heat flow in the garage (not directly anyway). As stated before why spend the extra money on the much larger pump if it's not needed. I found a 15-58 Grundfos on Ebay for about $60.00.....it seems worth the risk to me. Thanks for the input.

#1 Make sure the circ is a 15-58FC with the flow check built in or else plan on adding one in your piping.

#2. I would kindly ask you and everyone else here who may be in the process of sourcing system components to consider buying your stuff from a bona fide heating contractor or a plumbing and heating supply house. I spend a fair amount of time here just because I like to help people out and I have the knowledge and tools to do it. Chances are the place selling the 15-58 for $60 wouldn't know which end is the goesinta and which end is the goesouta. People in my area support me and I appreciate it very much. My business profit is what enables me to buy computers and programs such as the one I used to calculate your flow and head. I know that Joe and nearly any other contractor here would say the same. I'm not crying in my beer or whining about the internet sales thing by any means. I've bought and sold probably $10K worth of product in the last 3 business days via the net. Just asking you all to remember the local guy who will have a replacement circ or part when you need it some Saturday night or Holiday weekend.

 

[Huskurdu]

#2, point well taken. I appreciate your cander.

 

[gradwell]

After reading this thread I too have now become concerned as I also was told to run 1" from outbuilding to house 160 ft. each way, 320 roundtrip. I fortunately have not yet installed underground so can still correct.

In all of my Newbie no idea what I'm doing wisdom, can anybody give me advice as to pipe and pump sizing for my situation? My heat load total is 108,000 BTU/h. 24,000 BTU/h will remain in the outbuilding leaving me 84,000 BTU/hr to pump 160 ft. to the house which is elevated about 6ft. above outbuilding. The Pex run is a straight shot with 90' s at both ends to get into the buildings. No splices or fittings.

I have the ability to run upto two lines in each direction. I do have about 500 ft. of 3/4" O2 barrier laying around and thought maybe a 1" and a 3/4" each way may do the trick. What do you think and what size pump should I use?

I don't know what other info you may need to help me with this, but please let me know and I will suppy.

Thank you guys for your help.

Joe

 

[Willman]

Joe, check out the link in this thread by heaterman.

https://www.hearth.com/talk/threads/22206/

 

[MrEd]

I am getting to this thread late, so pardon my ignorance.

Everyone seems to be talking about only the distance from the OWB to the inside boiler, isn't it also necessary to figure out how much piping is in the house? and how would you do that? I have six zones in my 3000sf house, all mostly 3/4 or 1" copper, and 80% of the piping is all in the walls or otherwise inaccessible. How could one possible add up all the lengths, T's and elbows to figure out the required pump size? Yes, you can accurately add up the new run, but that only seems to be 1/2 or even just 1/3 of the problem...

My current boiler has one large circ, and zone vales. I figure new pump needs to be at least that big because if only the wood boiler is running, then the new circ needs to do all the work of the old circ, plus the added distance from tarm to the oil boiler.

Does larger pipe always mean smaller pump? I was planning on 1 1/4" pipe from the tarm to the oil boiler in the cellar, if I upsize to 1 1/2" pipe, and eat the cost now, does that mean for the next 20 years I can use a smaller, more energy efficient circ and save electricity costs?

Is there any downsize to the larger pipes?