Five port valve info

[asdex]

Hi, does anyone know where I can find more detailed information and maybe build instructions for a five port valve? With one of these you can connect a solar hot water panels to a low pressure hot water cylinder which only has the one hot and cold connection.
Attached is a diagram of one.
Thanks,

[Mike90250]

I've never seen or heard of one. What about the vendor who's watermark is on the photo you posted - can't you get one from them ?

[asdex]

No, they seem to have closed down.

[JSchnee21]

From the diagram provided, I don't see anything special. No "5-port" valve per se. Just two Tee fittings combined with some double male unions and some Swageloc or other soft copper compression fittings. You can easily buy all of this for less than $50-100 at Lowes. Or a better plumbing supply store. All of this can be had in plastic as well at a pool supply store.

When the tap is closed (right hand outlet), the recirculating pump which is running 24x7 (or on a timer for sunlight hours or based on a thermister in the array) takes water from the top outlet, recirculates it through a tank and the array, and returns it to the bottom left.

When the tap is open, cold make up water enters the system from the upper left. The pressure of the reirculating pump, proximity of the hot return, and the gravity induced head pressure from the tank/array ensures that most of the water going to the tap is hot. Additionally the upper tee fitting might be a "one way valve" preventing cold flow from the makeup inlet directly to the tap.

But, I've never seen a one way valve incorporated as part of a tee. So if you want to experiment with using a check valve (aka one way valve -- just a pipe with a flap that closes when pressure flows the wrong way) you would install it between the two tee's with the flow direction pointing "up" in the diagram above. Note that such valves may or may not be influenced by gravity depending on the flow rates at hand.

While such systems can be very effective and cost efficient for heating swimming pools, I've never really been convinced of the cost benefit for supplying hot water to a home. I guess in an off grid situation, if you don't have access to natural gas or propane and electricity is "free" (solar) it might be useful. But the cost of the electric to recirculate the water is pretty significant when compared to how cheap natural gas is these days and the water is not going to be very hot for very long.

[JSchnee21]

Note that by code, you will also likely need a check valve on the upper left inlet for cold makeup water to prevent your "potentially dirty" recirculating water from back flowing into the mains.

Also note that generally you don't drink the water that is being recirculated through the solar array because it can quite easily become contaminated with harmful bacteria. Generally there is a closed, recirculating hot loop, which transfers its heat to a fresh water take or heat exchanger which forms the basis of the cold loop from which you drink. A perfect example is a hot water storage tank associated with an oil furnace, The oil furnace has a forced, hot water re-circulation zone (think baseboard hot water) dedicated to heating the storage tank. The fresh water in the tank that you drink/bath in does not directly touch the water in the hot loop which gets re-used over an over and gets stale and contaminated with metals from piping / solder.

[J.P.M.]

Note that by code, you will also likely need a check valve on the upper left inlet for cold makeup water to prevent your "potentially dirty" recirculating water from back flowing into the mains.

Also note that generally you don't drink the water that is being recirculated through the solar array because it can quite easily become contaminated with harmful bacteria. Generally there is a closed, recirculating hot loop, which transfers its heat to a fresh water take or heat exchanger which forms the basis of the cold loop from which you drink. A perfect example is a hot water storage tank associated with an oil furnace, The oil furnace has a forced, hot water re-circulation zone (think baseboard hot water) dedicated to heating the storage tank. The fresh water in the tank that you drink/bath in does not directly touch the water in the hot loop which gets re-used over an over and gets stale and contaminated with metals from piping / solder.

I've been drinking water that's been circulated through flat plate solar water heaters for a very long time. All such devices I use have been code reviewed and approved. The components in a well designed and code approved solar DHW system are no more bacteria susceptible than any other DHW plumbing components.

Direct type systems were once common and always were (and still are) more efficient in most applications involving DHW applications than indirect types that use secondary loops and HX's.

Stating that water circulated through a solar collector can be easily contaminated simply by virtue of the system being a direct system is not correct.

Using a secondary loop for the purpose of helping to avoid freezing problems in most climates has become common and in more than a few jurisdictions mandated, but that's more for freeze avoidance than for anything to do with health reasons, which health reasons or thinking may actually be counterproductive, particularly if possible toxicity of the fluid in the circulating loop (the collector side) fluid is a consideration, or the secondary fluid is not maintained.

Indirect systems of that type also add considerably to the design complexity, cost and maintenance of solar thermal systems, particularly with respect to the considerations necessary to maintain the heat exchanger subsystem. To add to those considerations and making heat exchanger applications even more problematic from a design and efficiency standpoint, most HX systems used in code approved solar thermal DHW applications, if code does require an indirect system, usually require the HX to have either positive leak detection between the two fluids or a double wall HX, or both. The double wall is a maintenance and inspection nightmare even before the additional performance penalty of the double wall over single wall is considered. Most peddlers are absolutely clueless of such issues, or any notion of HX design and probably would avoid talking about them even if the had a clue.

For positive leak detection, it's almost or often easier and better from a serviceability standpoint to use two single wall HX's with a 3d fluid loop (H2O) in series with the other two and systems pressures lower from mains pressure to collector loop pressure, although the performance penalty for such a setup will be about equally as bad as that of a double wall HX. FWIW, I've never seen a 3 loop system, but my guess is if folks knew the performance penalty from crappy design of most HX's used in solar DHW applications, there might be more of them. They'd cost more, but they would meet the duty longer than a few years or less before fouling up.