Looking for a Hydraulic Control Valve of Some Sort

On the KISS basis, you might be able to eliminate a few components.

If each of the 5 circuits is the same length and fittings geometry, and if you use a looped return manifold, the system will be self-balancing (as done in ice rinks and the like). This could eliminate the balancing valves, most of the thermocouples, and one source of pressure drop.

I gather that that the pump will draw from the tank, pump to the inlet manifold, then through the circuits, then to the return manifold, and finally back to the tank. If everything can be arranged so that it grades up to the last point of the return manifold, with a final drop back to the tank, the top of the drop will be the high point of the whole system. Water pressure there will be essentially zero, +/-. If you provide a short standpipe there, say 2 feet, it shouldn't overflow. When the pump shuts off, the grid will remain full, and only the final return drop will drain to the tank. This eliminates the hydraulically piloted valve.

In case you want to drain the whole grid, put a manual bypass valve around the check valve, or maybe a temperature-controlled valve that drains everything automatically to prevent freeze-up under cold conditions.

You would still want temperature sensors on the supply and return lines, plus the ambient temperature one.

Neat project, looks like fun.

Hello Tornado,

Thanks for the advice. You have some great ideas there that I can use. Some of your ideas I have toyed around with in my noggin' for a while, but haven't put them down on paper or into the hydraulics software yet.

You are essentially correct in your assumptions about how the system will be set up. I have planned on installing a manual bypass around the check valve on the pump discharge line that also incorporates several isolation full port ball valves and a bleed-off port.

I regards to how I'm setting up the cold water feed lines to the manifolds, you're almost on the money. The cold water feed circulating pump does indeed draw out of the non-pressurized tank and conveys the water up to a horizontal "central" header-type manifold. From that manifold, I will be teeing off the individual feed lines that go to the 5 heat transfer manifolds; they'll feature throttling/isolation valves and small inline turbine flowmeters. No matter how I arrange these feed lines, I cannot get them all with identical lengths of run. [Some more info: each heat transfer manifold will be fairly long, and will have 10 evacuated tubes plugged in them spaced at 6-inches o.c.. There are a total of 50 tubes in the thermal collection system, with 2 spares in case there's a tube failure down the road.]. Conversely, the feed lines leaving the 5 heat transfer manifolds will convey hot water to another horizontal "central" header manifold (or return header manifold). These return feed lines will only feature isolation valves.

I like your idea of providing an increasing upwards slope on the return header (in the direction of exiting hot water flow and then providing a "standpipe" of sorts at its Apex. I take it that this standpipe is actually a 2 foot high U-shaped configuration of pipe and fittings? I think that would be an ideal spot to install the automatic air release valve and the manual air bleed would it not? I still worry that even if I install this standpipe, that a vacuum will occur due to the draining of the return line to the tank resulting in the siphoning of water from the heat manifolds. Are you absolutely sure that a standpipe will prevent this? Just playing the devils advocate and thinking "what if???". May be I'm thinking too much!!! LOL Please verify my assumption of how your "standpipe" will be configured. If I'm wrong, please do send me an emailed sketch, okay?

I'm not sure what you mean by the term "looped return manifold". Please explain, as it's not a term that I'm familiar with. Do you mean to construct a looped-type horizontal header manifold (cold water supply side) from which I'd branch off the 5 smaller feed lines to 5 heat transfer manifolds? If at all possible could you send to me a sketch via email of what you're proposing? After all, a picture is worth a thousand words.... Should I place this looped manifold higher that the 5 heat transfer manifolds and install an automatic air release valve, anti-freeze valve, and manual air bleed at it's apex too? Seems to me that this will be the most logical point to install the valves.

You're right, it's been a neat project so far. The fun actually begins when I can whip out the tube cutter, torch and solder and finally put it together after buying bits and pieces for the past 3 years!!!! YEEAAAAA!!!!! I've been wanting to build one of these solar systems since I was in high school back in the 70's and then throughout engineering school, even if I was a Civil Engineer. I figured that IF I couldn't build a "Mr. Fusion" reactor then I'd damn well had build a solar thermal system to heat the house!!! hehehehe My former Mrs., the X, had no desire for me to plan one on our restored 1896 Victorian so I didn't get around to doing this exercise until I met my more open-minded present wife...thank God common sense prevailed, especially after she saw how the home heating oil prices kept rising all last winter!!! ***LOL***

Again, many thanks Tornado!!!!

I have 5ea 200 gallon plastic tanks that act as a thermal battery for my system. They are not pressurized and can easily store the solar heat gain as you have concluded. I use one of those 10 dollar toilet bowl float valve to keep the tanks topped off, inside of a piece of 6 inch diameter PVC pipe.

I use a heat exchanger between the panels and the tanks to keep the fluids isolated (soft copper coils). I also use automobile transmission fluid in the panels. This eliminates freezing and over heating issues, plus the usual corrosion problems one has whenever water is coupled with metals. I'm able to store about useful 40 BTUs per pound of water with this system.

To augment this system I'm currently installing 2 panels from Cansolair. http://www.cansolair.com/. I believe this to be the best air collection system on the market. This keeps the home warm during the day so that I can use the other system at night. ( I have no interests with Cansolair, and am not compensated by them. There's something going on with blog endorsements through proposed or current legislation; just wanted to be clear on this!)

Hello Shaupt,

A couple of more great ideas! Thanks for the advice!

I do have a couple of questions for you as I'm not sure what you meant in your comments.

Are you using the automotive Tranny fluid inside of your solar panels only, or are you using it throughout the entire system? If that's the case, using over 1,000 gallons of transmission fluid is quite a lot, and seems to me very expensive. Maybe my guess is off base. Or, are you mixing water with the transmission fluid, or are you using it inside a closed pipe loop system and using heat exchangers to transfer the heat to the water stored inside of the 5 tanks?

Just curious, are you using plain old polyethylene plastic tanks and how are they holding up to the heat? BTW, what's the maximum fluid temperature reaching the tanks? Also curious where you found your tanks...

I like the idea of using the toilet feed water valve to keep your tanks topped off! Clever idea! I just hope you have an overflow line to a floor drain or sump pump basin in case it doesn't shut-off!!!! Good old Murphy's Law prevails always in regards to toilet bowl float valves and ever running toilets!!!

Again, many thanks!

The system uses about 5 gallons of transmission fluid. The solar heat from this fluid is cooled by the water in the storage tanks through soft copper coils (about 5/8") from The Home Depot. The water in the tanks is just ordinary tap water. These absorbers are of a new design and I am current working on a provisional patent.

I purchased the 200 gallon plain old poly tanks from a farm supply store up in Pennsylvania (Southern States). That part of the project was completed about three years ago. I'm sure if you searched the web you could find these tanks in stock closer to you. I recall paying just over $200 dollars for each tank, plus tax, three years ago. They're about 36" x 72" tall cylinders. I really didn't want to spend over $1 per gallon for storage. The plastic is different than that used for a gallon of milk. It is tougher and is yellowish in color. The openings in the bottom are about 3" as I recall. Each tank has its own valve for maintenance reasons.

I've had the water temp to 103 degrees F. That was due to the capacity of the collectors. I'm sure they would hold up to 115 or so. All of the plastic pipe is PVC, not CPVC, as I never intended the water to get that hot. The weight of the water in the tanks, if hot enough, would cause some sort of sag failure, I'm sure, but I think you may have to pretty much boil the water for that to happen. These tanks are used outside and during the summer for many farm applications so they are designed to get hot. At 103 degrees the tank plastic is still quite rigid. There are 10" black plastic screw on lids on the tops of the tanks. This season I'll shut off two of the tanks and see how hot the water gets.

My prototype water-to-air heat exchanger was a car radiator with a $16 dollar fan to see if 100 degree water would be warm enough to heat the air. It is a bit lame, sort of like the air you get from a heat pump unit. I am currently working with abpapst in Germany to get more respectable fans.

I have only needed to replace the toilet tank valve once. The valve on the supply line to the fill valve is hardly turned on, so the failure was not that catastrophic. I'm more worried of a mouse chewing through some of the PVC just for a laugh, though.

Regards,

Steve

A looped-return system can be visualized thus:

Draw a horizontal line somewhere down the page; this will be the inlet manifold. The pump feeds into the left end, and the right end is capped. Somewhere above this, draw a parallel line; return manifold. Here the left end is capped, but the right end then turns 180 degrees (up and back to the left). Using a tee at this uppermost point, enter via the branch. The downward run goes back into the tank, near the bottom to prevent splashing; the upward run is the standpipe, with a gooseneck on top.

Branch off as many circuits as needed from the inlet manifold, going up into the return manifold. Note that the total flow paths through every circuit are thus the same length, thereby equalizing pressure drop (and hence flow) among all circuits. Unless there is a concern about leaks in an individual circuit, no valves at all will be needed in the grid; only those associated with the pump, discharge check valve, and make-up valve to the tank.

If your individual circuit lengths vary less than say 30%, the flow rates per circuit will vary less than 14% (sqrt 1.30 ~~ 1.14). This should be acceptable, because there is no need to have absolutely uniform temperatures across the grid.

Your inlet and return temperature sensors can now be located near the pump/tank, with possibly an ambient sensor through the wall to a shaded location. This concept is also used in glycol underfloor heating systems to keep ice from forming beneath freezers or driveways. In those cases, PEX tubing is often the material of choice.

Hmm, while you're at it, you might be able to expand this into a snow-melting system!

Hello Tornado & Shaupt:

Thanks guys for the advice!

Tornado: I think I get what you're driving at with your manifold layout, but I'm still concerned that your standpipe device isn't prevent water siphoning from the return header as the heated water flow back to the tank in the return line. just not convinced at all that it'd work. Doesn't Watts Regulator or some other valve manufacturer produce a hydraulically piloted Anti-siphon/Breaker or Isolation flow control valve for 3/4-inch diameter pipe? I've used Ross' (from Troy, NY) hydraulically piloted isolation control valves in municipal water distribution systems in the past, where we have extremes in topography. We needed to create or maintain those different pressure zones as well as prevent siphoning and vacuum conditions from occurring. Nothing worse than a large ductile iron main going into vacuum and then collapsing! Also, we had to prevent blowing-out of water pressure regulating valves on city resident's hot water tanks, as well as over pressurization of old plumbing inside houses and street mains in the lower level pressure zones, etc.. Some of these valves were located on 16-inch, 24-inch and 30-inch diameter ductile iron water mains, and involved building fairly large underground reinforced concrete valve vaults. I know those types of valves work, and could work here in my contraption too. I'd rather spend the money and sleep well at night knowing that the manifolds won't drain. Again, the key thought here is to keep the manifolds at 180 degrees F and full of heat transfer water so as to prevent the creation of steam in the manifolds, which if it occurred would be a big no no.

Shaupt: Glad you were able to find some rather inexpensive plastic tanks! In your case your highest temps shouldn't be a problem. If they're regular poly plastic tanks then they're probably rated for up to max 150 degrees F Working temp. In my case, my solar thermal collectors will be mounted on my yet to be completed 2-story steel toolshed/storage building that'll be located about 45 feet away from the house. [I'm in the process of fabricating the trusses and columns now]. I plan on super-insulating the supply and return lines with a high-tech thermal insulating paint (several coats) as well as wrapping the lines with several inches of rock wool and then a final wrap of a radiant foil. Both lines running between the house will be inside a pair of buried 4-inch diameter PVC Sch. 40 carrier pipes. I don't envision that I may loose much heat in the return line, so I have to plan on the thermal storage tank/battery to hold at least 180 degrees F hot process water. I've already bought my 600-gallon storage talk that features special poly plastic to withstand the temp (up to 200 degrees F) and has factory applied rigid insulation. All pipe ports have already been cast into the tank at the factory. Ditto with application of required thermocouples. All I really have to do is wrap some radiant foil around the tank and attach the various pipes for the thermal system and the domestic hot water lines that also include my fabricated SS parallel-plate heat exchangers.

Again, thanks guys!

===Mark (aka CaptMoosie)

A standpipe like this is simply an elementary form of vacuum breaker. Most conventional vacuum breakers incorporate a floating element that rises and plugs an orifice/port when liquid is present, and are typically used in pressure systems. If the system loses pressure, the float drops away from the port, admitting air to break any siphon effect. Such a device would work in your system, but it costs a few $, more than a couple feet of pipe.

Unless the final down run of your system is too small (restriction), there should be essentially no pressure at the top, hence no need to close any port. If nothing else, you could start with the simple standpipe. This is all but guaranteed not to fail, but if for some weird reason it does, you can add either a vacuum breaker or piloted valve later.

Sometimes overengineering leads to worse problems than underengineering, starting with excessive initial cost. But then money is no object...so long as it is someone else's money!

If you want to prevent every last bit of water in the return header from draining, just before it enters the down run, you can offset upward with two close-coupled 45's.

Hello Again Tornado:

Could you send a pic or sketch to my email in regards to what your standpipe device would look like. I'm having a difficult time trying to visualize it and how it work to stop the return manifold from draining at all. I still think I may want to keep that manifold at least under a tiny bit of back pressure or from draining just a little bit. The reason why is that even if my chemical feed pump (low flow delivery rate and moderate TDH estimate) kicks on, it'll take quite a while for any new coolant water to arrive to the heat transfer manifolds. I've already purchased the pump surplus, but have yet to choose a new pump head. That'll be done after I run the hydraulic modeling software.

IF needed, I don't mind a buying a hydraulically-piloted globe valve that serves as a back-pressure sustaining valve as long as it costs less then $250 or so. I'd rather sleep good at night knowing I don't have to worry that the manifolds are full of water. Do you know if Watts Regulator makes such a valve, say for 3/4-inch line? If I have to, I can always increase the line size....but still wonder if I can meet the inlet and outlet pressure range requirements where a pilot has to operate under. I may nee to boost the inlet pressure (as in the return manifold) enough for the pilot to operate satisfactory!

I agree with you 100% about not over-engineering the system and keeping it KISS!

Are there any other manufacturers that I could look at?

Again many thanks for the help!!!!

I would be glad to do some sketches and email them, but I haven't yet seen your email address. CAUTION! If you don't want lots of spam, don't give the address in normal email format. Replace the "at" symbol with something like -at-. Otherwise, various bots in violation of Asimov's laws will pick it up and inundate you with garbage.

(Note CR4's repeated warnings about this.)

It looks as though my older AutoCAD Lite (and older computer) will not export to .jpg files, or whatever can in turn be imported as images into CR4 threads. I may be overlooking something easy here; suggestions are welcome. But at least I can do .dwg and .dxf files as email attachments, if you can open either of those.

Hello Tornado,

That would super if you could send a *.dwg or *.dfx format darwing file to me. I have a version of IntelliCAD PE that's about 4 years old, so sending a file from your AutoCAD Lite shouldn't be a problem as long as it predates 2005.

My email addie to beat the spybots: captain0612atfrontier.com

Again, many thanks Tornado for your help, and please, have a great weekend up there in AK!!!! Beautiful country that you live in. Someday I shall revisit it again with my wife in tow this time!

Thanks,

Mark

Hello, I have a few ideas you might check into for your system. You may already have this information but you may not. I tend to take on unfamiliar projects as a way to acquire things I can not afford to just buy outright such as equipment or tools and so on for my welding shop, scuba diving and glassblowing. The other reason I like to do these projects is that I enjoy the challenge as well as to make myself learn something new. It never hurts especially when designing/building something that is new and/or unfamiliar to get all the ideas on the table so you learn as many angles as you can and get a good plan before you start. I have proven this to myself many times in the past 3 years while building the components and equipment for my glass blowing shop. If I had researched and learned more about different glassblowing equipment and then planned more before I started I am sure I would have skipped building a gas fired melting furnace all together. I would have saved a ton of time, money and trouble by learning about and building the electric furnace to start with. Another thing I have learned from these special projects (Imany times I learned these things the hard way)is that a simple design is usually better than complex design and it is always a hell of allot easier to build and maintain.

I would suggest checking into Honeywell for your control valves. The 3 way type that are used to control and balance chilled and hot water A/C systems sounds like what you may need. The valve can be adjusted to automatically by-pass at a certain temperature that is monitored via a small pilot line or temp switch. I have installed many of these in the past and they are very reliable valves. There is also a valve called a circuit balancer that is used on a/c lines to balance circuits in the system that may be worth you checking on. I can not remember who makes it but it is a common valve company and I can get you a name if you don't already know of these valves.

If you need to have a back up system you could use a cheap level switch on your tank, 2 solenoid valves and relays to override the (fail open?) control valve and keep up the tank level if the control valve stopped working or your pump dies. I would run a separate by pass line and use couple of the Red Hat brand common solenoid valves (new old stock Red Hat solenoid valves and good relays sell cheap on Ebay) one normally closed in the by-pass line and one normally open in the main line upstream of the control valve. A temperature switch can also be used to control these valves or you could add another solenoid valve and/or extra relays if you want to be able to control the temperature and level if your pump or control valve dies.

You may also need to install a check or backflow preventer valve in certain places where you may want to keep your water from flowing back when the pump shuts down or any other reason. You can avoid having to install a back flow preventer or check valve in your make up water line if you install it to feed from above your tank to keep the water level from rising over the bottom of the inlet pipe. If you are interested in installing the make up water this way and because it is an "open system" you may want to look at installing an overflow drain at or just above your desired normal operating level This will give you a fail safe way to keep the level from getting to high in the tank as well as allowing you to control and direct any water that might overflow to a sewer instead of on the ground.

I would suggest that you pipe the manifolds in a reverse return arrangement because this will make your system naturally more balanced to begin with and will eliminate a ton of tuning with valves to get it balanced afterwards. In a reverse return system the first item supplied with water (hot or cold) is the last item that back into the return line. I have installed this type of return in a/c pipe systems on many jobs and they do work and are worth the time it take s to do them IMO

If you want use manual control valves to control flow/pressure at each manifold I would suggest using a globe valve, they are readily available in small sizes and made in many different materials. Globe valves are great for controlling flow and pressure. A V-port knife gate valve will also do this but I I'm not sure if V-port valves are available in a pipe size less than 2". The use of these valves will allow you to tune the system so that all the manifolds get equal flow and pressure and unless you can get each line to have equal lengths of pipe and fittings in your system this type of valve may what you want.

I hope this helps and good luck with building your system