[Pops]

Tempering valve:
http://www.watts.com/pages/learnAbout/t ... asp?catId=

[vtsnowedin]

Most of the pressure relief valves I am seeing on line are rated for 150psi and 210 degree F. Does this mean that the valve only opens at this psi and temp range when the water would actually start boiling? If so is this the right one for this system?

Water boils at 212 so a relief valve set at 210 opens before it boils and makes steam. The outlet of the valve needs to be carried down close to but not touching the floor so the scalding hot water can't strike a human or pet if it opens.

[Pops]

Thanks VT, I was afraid of that

I made a tank for the greenhouse out of a series of 55gal plastic drum and had to order some fittings to go through the sides of the tank, I assume you can make it work through sheeting

http://www.mcmaster.com/#tank-fittings/=sbh92x

Or just get the painted steel tank shown here and stand it upright. http://www.mcmaster.com/#hot-water-stor ... ks/=sbhgxt
The 80 gallon one for $560.05 would work like a charm.

You can also use an electric water heater, take out the top and bottom element and plumb them into your collector, plumb in

Or take out only the top element and plumb your collector hot return into that fitting and come off the drain valve at the bottom to supply to the collector. That gives you insulated, thermostated, electric back-up heated solar hot water.

[vtsnowedin]

[
Or take out only the top element and plumb your collector hot return into that fitting and come off the drain valve at the bottom to supply to the collector. That gives you insulated, thermostated, electric back-up heated solar hot water.

Yup that would work.

[Ibon]

Or take out only the top element and plumb your collector hot return into that fitting and come off the drain valve at the bottom to supply to the collector. That gives you insulated, thermostated, electric back-up heated solar hot water.

That is a great idea actually. what I could do is replace the bottom 4500W heating element with a 1500W heating element. On our hydro system we have a dump load that is burning off unused power. It is divided into several 1500W channels. It is about 250 meters from the lodge so for the cost of one small gauge cable from the hydro to the lodge I could put the first of the 1500W dump channels (which is usually dumping power) and connect this to the replaced 1500W lower element of the hot water tank. On those rainy days with no solar heating the 1500W wont cut it but I have the back up on demand gas.

THere are 5 bedrooms in this lodge each with their own hot water shower. Let's imagine the following scenario. 8 guests go out on a walk, it starts to rain, they come back cold and soaked and all want to take a hot shower within the next 30 minutes. How big an electric hot water tank do I need? Is 80 gallons enough and how large would my solar collector surface area need to be to heat 80 gallons of water on a sunny day??

I could also make an extra insulated storage tank and still incorporate the electric hot water tank as Pop's suggest. This idea is good also because I have a 40 gallon one in storage on site that I haven't used since it was draining to much of my hydro power and I replaced this on another cabin with on demand gas.

I have to think this through but good ideas. Thanks

[Ibon]

I got this from a site on the diameter of the thread on electric hot water tanks that the elements get screwed into.

The thread is a 1" (diameter) x 11-1/2 NPSM thread and is standard for all residential water heaters that use screw-in elements.

In Panama I have problems finding fittings so I want to get this before I leave in a couple of weeks. I need the fittings to adapt 3/4 inch CPVC pipe into this thread. Where do I find this? Any ideas?

[Newfie]

Try grainger

http://www.grainger.com/product/EATON-M ... pp%3Dfalse

Or Eaton
http://www.eaton.com/Eaton/ProductsServ ... 259#tabs-1

Or Parker hydraulics
http://ph.parker.com/us/en/fittings

[vtsnowedin]

Or take out only the top element and plumb your collector hot return into that fitting and come off the drain valve at the bottom to supply to the collector. That gives you insulated, thermostated, electric back-up heated solar hot water.

That is a great idea actually. what I could do is replace the bottom 4500W heating element with a 1500W heating element. On our hydro system we have a dump load that is burning off unused power. It is divided into several 1500W channels. It is about 250 meters from the lodge so for the cost of one small gauge cable from the hydro to the lodge I could put the first of the 1500W dump channels (which is usually dumping power) and connect this to the replaced 1500W lower element of the hot water tank. On those rainy days with no solar heating the 1500W wont cut it but I have the back up on demand gas.

THere are 5 bedrooms in this lodge each with their own hot water shower. Let's imagine the following scenario. 8 guests go out on a walk, it starts to rain, they come back cold and soaked and all want to take a hot shower within the next 30 minutes. How big an electric hot water tank do I need? Is 80 gallons enough and how large would my solar collector surface area need to be to heat 80 gallons of water on a sunny day??

I could also make an extra insulated storage tank and still incorporate the electric hot water tank as Pop's suggest. This idea is good also because I have a 40 gallon one in storage on site that I haven't used since it was draining to much of my hydro power and I replaced this on another cabin with on demand gas.

I have to think this through but good ideas. Thanks

I'd think that ten gallons of hot water per person should be enough. And you have the electric and on demand heaters working as the water is drained which might give you another twenty gallons or so during a half hour shower period. And human nature says that not all will hit the shower at the same time. some will hit it as soon as they get to their room and others will kick back and have a drink or fiddle with their new girlfriend then get around to shower just before dinner. I don't have figures for collector size in the tropics but they should not be too hard to find on the internet. If you make it too big you can always throttle the cold feed with a half closed valve. How dependable is the 1500 watt dump load from the hydro gen set? If it is intermittent it might be the weak link in your system.

[vtsnowedin]

I'll bet that cruse ship designers have a set of tables that show how much hot water they need when all 3000 passengers come back from their day on shore. It shouldn't be too big a secret.

[Ibon]

Try grainger

http://www.grainger.com/product/EATON-M ... pp%3Dfalse

Or Eaton
http://www.eaton.com/Eaton/ProductsServ ... 259#tabs-1

Or Parker hydraulics
http://ph.parker.com/us/en/fittings

Thanks Newfie. Pops suggestion to use an electric hot water tank and run the piping into the thread where the heating element goes has taken me down a long and windy road calling many suppliers and coming up with still no solution. The Grainger link you send with that fitting needs to be NPSM male to NPT female, the reverse. The NPSM threads on hot water tanks are unusual when it comes to finding fittings. I might have to go to a machine shop in the end and have something made if I am going down this route.

[Pops]

NPSM have the same thread pitch as NPT but are straight whereas pipe threads are tapered. The fitting you need will have an O ring, like a hydraulic hose to make a seal. It's called ORB for O Ring Boss.

[Ibon]

NPSM have the same thread pitch as NPT but are straight whereas pipe threads are tapered. The fitting you need will have an O ring, like a hydraulic hose to make a seal. It's called ORB for O Ring Boss.

Right. In the last 24 hours I learned this as well. Your suggestion to use an existing electric hot water tank got me going on this because I have a 40 gallon one in storage up the mountain in Panama.

The problem is that there are no off the shelf available fittings with 1 inch male NPSM threads. There appears to be no standard applications for this. I chatted with a Grainger tech support who transferred me all the way up to supervisor and came up with nothing. I have an e-mail waiting with Eaton and another with a major plumbing supply co. I talked to another service rep on the phone.....all coming up blank.

Just to review for anyone new reading this........I want to connect a 3/4 CPVC pipe into the female 1 inch NPSM of the hot water tank where the threaded heating elements go.

[Pops]

How about this page
http://www.discounthydraulichose.com/product_p/6405.htm

this item
6405-16-12 | #16 SAE/ORB Male x 3/4" NPTF Female

then just straight npt union?

I think that's right, worth a call.

[Pops]

And if That doesn't work, get Newfie's fitting, a short straight pipe nipple and an O ring; thread the straight pipe into the Female fitting, put the O ring on the pipe and tighten 'er down on the water heater.

[Pops]

Just for those observing, NPT is National Pipe Thread and it is how all domestic plumbing is threaded, the male and female are tapered (male is smaller diam at the end and larger diam toward the pipe) so that as you tighten them the threads deform and that makes them watertight.

Straight pipe looks the same as NPT but there is no taper, so just like a nut and bolt you can keep turning forever and until they come up against a stop (the head of the bolt for example) they never tighten. Straight pipe uses a washer or O ring to make the seal.

Usually high pressure systems i.e., steam and hydraulics don't use NPT because to be able to deform the pipe must be soft ("lead" pipe) and being soft, it can strip out under pressure. Straight pipe doesn't need to deform to make a seal so the material can be harder and the connection stronger.

Probably the reason straight to npt adapters are rare is to keep people like me from blowing their fool heads off cobbling up some galvanized pipe in a 2,000psi hydraulic system - which btw I've seen but not been guilty of personally.


ETA, too bad Patience isn't around much, he knows all this stuff.

[MD]

you need a cheap frequency drive connected to a small 3 phase circulating pump motor with a feedback loop from an analog temperature sensor that is positioned at the hottest part of the loop.

less than $400 for the components.

[Scrub Puller]

Yair . . . bloody hell fellers, I don't believe this conversation.

The fitting is called a "bush" threaded externally (male) 1" NPT (or BSP) and internally (female) 3/4" NPT (or BSP) . . . just glue a male adapter onto the PVC and you are in business . . . put 1" NPT x 3/4" NPT bush into Google images and thousands are shown.

Or am I missing something?

Cheers.

[vtsnowedin]

you need a cheap frequency drive connected to a small 3 phase circulating pump motor with a feedback loop from an analog temperature sensor that is positioned at the hottest part of the loop.

less than $400 for the components.

Isn't a cheap three phase pump for $400 a contradiction in terms?
If he needs a pump at all why not a solar powered unit (One gallon a minute wold be enough) that turned itself on when the sun hit it and the collector and turned itself off when the sun went down. Might even be variable so the hotter the sun the faster it went.

[vtsnowedin]

Yair . . . bloody hell fellers, I don't believe this conversation.

The fitting is called a "bush" threaded externally (male) 1" NPT (or BSP) and internally (female) 3/4" NPT (or BSP) . . . just glue a male adapter onto the PVC and you are in business . . . put 1" NPT x 3/4" NPT bush into Google images and thousands are shown.

Or am I missing something?

Cheers.

How do you get your hand and wrench inside the glass lined water tank to hold the inside half of that fitting.
If the hole has threads, and it does, you just have to find a fitting or adapter of that same thread. might need some pipe thread compound or you could even solder it in. Once you get out to 3/4 copper either thread or sweat solder you can adapt over to whatever pipe you want to run to the collector.

[Pops]

put 1" NPT x 3/4" NPT bush into Google images and thousands are shown.

Or am I missing something?

Cheers.

Yeah, the tank isn't taper threaded (british or national) it's straight, so a taper bushing won't work under pressure. Taper threads would only be holding by the last couple of threads, if that. It would be a drag if it pops and burns your birkenstocks off!

If that last fitting I linked won't work, I did find a stainless nut and silicone O ring made for just this application. All you need is a short straight pipe nipple and any of the female nps to male npt adaptors will do it.

http://www.bargainfittings.com/index.ph ... duct_id=95



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