Hydraulic Separator Storage, delta T boiler Circ, delta P load C

Hi All,

It has been a while (again). The design I have attached is my final stab at making things as simple and efficient as possible and I will be ordering parts as soon as this thread has run its course. The boiler room has been invaluable to me so I have included a lot of info in hopes that this post might be useful to those taking their first look around. If this is all old hat my apologies to you for the lack of brevity. Do your worst.

Diagram Legend.
A. 007 Taco Delta T Circ http://www.pexsupply.com/Taco-007-VDTF5-007-Variable-Speed-Delta-T-Cast-Iron-Circulator-Pump-115V sized with http://www.taco-hvac.com/uploads/FileLibrary/SelectingCirculators.pdf
B. Danfoss Mixing Valve
C. Watts Air Separator http://www.pexsupply.com/Watts-0858548-1-1-4-AS-MB-Microbubble-Air-Seperator
D. 86 GalPressure Tank http://www.pexsupply.com/Amtrol-150N32-THERM-X-TROL-ST-210V-Expansion-Tank-86-Gallon-Volume
sized with http://s3.pexsupply.com/manuals/1260456456055/20376_PROD_FILE.pdf
E. Storage – 2 horizontal 500 gal. tanks welded to be hydraulic seperators
F. Grundfos Delta P Circ http://www.pexsupply.com/Grundfos-59896832-ALPHA-15-55-F-LC-Cast-Iron-Circulator-Pump
G. Mixing Vavle for Radiators http://www.pexsupply.com/Taco-5004-C2-1-Sweat-5004-Mixing-Valve-3653000-p
H. Mixing valve for Radiant Floor http://www.pexsupply.com/Taco-5004-C2-1-Sweat-5004-Mixing-Valve-3653000-p
I. DHW Circ - not sure what to use here-- any thoughts on something cheap? 1 GPM and 1.5ft head
J. BioMass 40
K. Taco Zone Sentry Valves http://www.pexsupply.com/Taco-Z075T2-1-3-4-Zone-Sentry-Valve-Threaded
L.Watts 125 psi relief valve http://www.pexsupply.com/Watts-0156481-3-4-40XL-5-TP-Relief-Valve-125-psi-12821000-p
Questions
1. Control suggestions for the DHW circ?

2. Should their be an air separator or float vent at the top of storage.

3. Is the air separator/expansion tank location ideal?

4. I want to use a Grundfos Alpha as my load circ but I am not sure how its control works and how it would "see" the different heads and flows of the radiant and radiator zones. Here is the specs as well as I am able to calculate:
-10 loops radiant - these are serving a 40000btu/hour load so the max flow per loop is .4 gpm but The taco circa sizer (http://www.taco-hvac.com/uploads/FileLibrary/SelectingCirculators.pdf) says that minimum flow in 1/2" pex should be 1.2 gal per minute. At this flow the max head is 16.56 ft. The loops are grouped in to 3 zones
1 of 5 loops - 2 or 6 GPM
1 of 3 loops - 1.2 or 3.6 GPM
1 of 2 loops - .8 or 2.4 GPM
- 4 Zones of Radiators all having flow below 2 gpm and head below 2 ft.

How will the ALPHA ensure enough flow in the different zones based on pressure changes. Is it big enough in general? Here is its pump curve- http://www.pexuniverse.com/sites/default/files/imagecache/product_full/aplha%20perf_c.jpg
5. I know my tanks have some scale in them. Do I need a sediment filter?

6. Total system size is roughly 1140Gal - 1000 gal storage, 40 gal boiler, 100gal for everything else. The THERM-X-TROL ST-210V Expansion Tank (86 Gallon Volume) has a capacitance of 46.44 gal. I calculated using http://s3.pexsupply.com/manuals/1260456456055/20376_PROD_FILE.pdf a requirement of 41 gal. Does this seem right?

7.How does one size load mixing valves? do I need 3/4" or 1".

8. Where should I have isolation valves, check valves, drain valves, fill valves and other basic fittings.

9. Controller ideas to turn on the electric boiler only if there is a call for heat from a zone and the temp in the tanks is below a certain point?

10. Is delta 35 deg F a good assumption for radiators?

11. Water treatment suggestions?

12. Any and all thoughts, suggestions, critiques or comments would be appreciated. I bought my BioMass and had my tanks made 3 years ago this past fall based on readings here in the boiler room and it is relieving and exciting that i finally have the time, budget and brain space to get this system up and running. What a strange and wonderful journey.

Thanks

Augie

Nice to see someone else from North Nova on here.

Looks like you've put a lot of thought in & are well on the way. I don't have much to offer right now on your specific questions, but do you have provisions for a dump zone or overheat protection - say in a power outage? I also have an electric boiler for backup, but plumbed it so it bypasses storage with its own circ when it's heating (I should maybe update my plumbing diagram & put it in my install thread). I didn't want to send any electrically heated water to all my storage - but the way you have it done it might not matter, as long as your tanks are well insulated. I just transferred all my controls from my old boiler, they fit right in pretty good. If I had to explain it all from scratch, I couldn't - but an L8124 used to kick my oil burner on when the boiler temp dropped to a certain point & there was a call for heat, I'm now using that circuit to close the thermostat contacts on the electric boiler. I haven't got that part all wired up yet - I needed a relay which I now have but haven't gotten around to putting it all together. I didn't do any water treating, just sealed it up & started heating & pumping. I put one Wye strainer on just before my laddomat, my tanks seemed to flush pretty clear when I pressure washed them. Wyes are pretty coarse, but there wasn't much in it the one time I drained it. Took a long time to find a 1-1/4" one here. I think people have found two smaller expansion tanks to be cheaper than one big one - SX110v's? I just used a 100 gallon propane tank as a non-bladder expansion tank (was also way cheaper) - I'm not sure how it will stand the test of time yet though. I put three air bleeders in, just picked three high points. I can let air out of the tops of my tanks via ball valves on vent ports. I've got a sidearm for DHW - plumbed in a ZV on the A side but it's not wired yet. I am just going to try a regular hot water tank thermostat strapped on to the DHW tank somewhere (maybe on the DHW inlet to the sidearm) to turn the 24v to the zone valve off & on. A snap switch would likely work too if you could get the right one. The ZV has an end switch in it that I might end up wiring to my load circ if things don't flow good through the A side by convection (I'm in the middle of replumbing the sidearm arrangement - didn't get it in the right place the first time).

BTW where are you getting all your supplies? I had a heck of a time finding some things around here.

Hello Augie,

I am also going with the storage as hydraulic separator approach. I like the simplicity and my heating side only requires 120max supply temp, so I wasn't to concerned about the boiler being able to supply the loads directly. Obviously if you need higher supply temps to your loads than this type of setup *could* be slower to provide usable heat.

Regarding Maple's comment on overheat protection-I think you could have a nice opportunity to utilize storage as most or even all of your overheat strategy assuming a few things:
Very close proximity of boiler to storage, top of storage located as high as possible above boiler, oversized piping with minimal fittings, bends,etc., constant rise from boiler supply to top of storage, constant fall from storage to boiler return if possible. Also maybe consider a loading unit as they are kind of optimized for this type of setup. They are pricey, but when you figure isolation ball valves, unions, temp gauges, return water protection, 3 speed pump, low resistance check valve to maximize thermosiphon in power outage/pump failure, they start to look pretty good IMO.
Of course for this overheat strategy to work it means always having some capacity in storage, but as you will be batch burning it probably wont be to hard to figure things out. And in the end this still might not be enough over heat protection but I think it is worth using whatever you can.Whew, hope that rambling makes any sense.

Expansion-I think you may need more than what you are figuring. The tank your looking at has enough acceptance volume but the overall volume may not be enough-meaning you might need more air volume on the bladder side of your tank(s) to keep your pressure below your relief valve setting, Which should be 30 psi NOT 125 psi.

To me these systems are too expensive to not think about water treatment. Mike at http://www.woodboilersolutions.com/ is top notch. At least think about a pre cleaner.

Noah

If the wood boiler is not fired does the electric boiler need to heat 1000 gallons to provide DHW? Or is that a DHW tank with a burner or element?

Thanks for the responses,

Floydian -I am hoping that my storage will serve as overheat protection, it is within 10 feet of my boiler and will be plumbed in as described. Can you explain more about pressure tank sizing? How do you determine acceptance at a pressure?

Bob- the DHW tank has electric elements in it

maple1 - why three bleeder valves in your expansion tank? I haven't started sourcing stuff yet. I have family down in maine so I may order online to them and them take a spin down there to pick it up. If you are looking for anything specific let me know and I might be able to get it on the order.


Thanks

Augie

I meant three bleeders around my system - not on expansion. Guess that's what happens when a fellow writes a long rambling paragraph.

Good luck with things - I'm hoping to not have to buy anything else. Or not much more at least.

Lots of Questions. a few thoughts!
I used storage tank for Hyd sep on my system. It works good. Can't use system without storage though.
I'd install y strainer.
Isolation /purge valves for each zone at minimum in case of breakdown
Not sure If I would flow to zones thru the electric backup?
The oo7 for main boiler pump? Might need to move more GPM. It tops out at 12 Gal/min at 0 head. Might consider a loading unit 3 sp pump/isolation valves/return protection all in one?
1.Can use simple aquatstat to control DHW circ. A strap on or a remote bulb aquastat attached to water jacket of DHW heater for better control
2. I'd recommend an air vent at top of storage
4. Most systems use 30 psi relief valve?
5.Can use break on rise aqua stat to keep back up boiler off when storage is hot
I found a lot of good info on system design off the tarm Biomass website

Why?

From the curve i looked at (http://www.pexuniverse.com/docs/pdf/100-1.8.pdf) the 007 will move 20 GPM at 2 feet head which is where I am at with my system (boiler very close to storage)
Advice taken on relief valve and air vent on storage.
As to the aquastat - can you explain if this would allow me to prevent pumping water even if my storage was too cool to justify it. In that situation I'd like the elements in the tank to heat my DHW but only then.

Thanks

Augie

Augie

My bad on the 007, I looked at the curve backwards. you are correct.
On the aquastat, you bring up a good point. I think you would need 2 aquastats wired to control the one circulator, 1 would be to keep water in the desired temp range with sensor bulb at wter heater and a 2nd make on rise aquastat with bulb on storage tank to keep the DHW circulator off unless water was at a min temp in the strorage tank. Elec power would go to the storage tank switch first. I have heard talk on this site about doing this type of stuff with snap disc switches. The switch on the storage really does not need to be a diffferential type, just makes at a certain min temp. I have a similar situation. I unplug my DHW circulator when temp falls below min, which is rare when operating the boiler, but it is not automatic.

Another possible way I was thinking about doing this on my system so I don't have to unplug the circulator is to use a 240 V coil relay to switch 120V so that if water heater kicks on because water supply temp from storage is below desired, it would switch off the circulator pump for DHW loop. (It is on my list to do anyway!) I think it would be anormally closed relay configuration. When 240 V is supplied to the water heater, the 120V switch opens to prevent circulator from running. The water heater temp would be set just below the circulator aquastat setting. I don't see why it would not work. Maybe someone else here has thoughts on this.

Augie, this thread has a lot of good info on the subject. http://www.hearth.com/talk/threads/expansion-tank-volume.51241/#post-642119

My preference was actually an open expansion tank as the highest point of the system but my Varmebaronen requires the open expansion tank be located min. 8 ft above the highest emitter and I couldn't achieve this so I plunked down for two Flexcon SXHT 110's for a total volume of 124 gallons and an acceptance volume of 50 gals for a 1060 gallon total system.

Noah

Noah, is your boiler up & running? And what model do you have?

Just don't remember seeing any pics or install info - with my ears for all things Varm.

Hi Maple,
Vedolux 37-keepin' my fingers crossed for the 1st fire(s) this weekend. We'll see.

Pics will follow at some point.

Noah

You should be able to coast for a couple of days on that storage - especially with this (not real cold) weather. Will watch for the pics!