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Prop and Zone Valves — Parallax Forums

Prop and Zone Valves

JonathanJonathan Posts: 1,023
edited 2015-01-30 20:44 in General Discussion
Hi All,

I recently purchased a 40 tube solar thermal heater for my hot tub, replacing my old flat plate heaters. I'm going to be making a real fancy solar powered tub this time and I want to use zone valves, at least I think I do.

I'll need at least two 3-way valves and a couple of 1-ways. My questions are:

Any brand recommendations?
I see different configuration. Are some easier to drive than others?
Seems like most are 24VAC control, so should be able to get some SS relays.

Any information on zone valves at all appreciated.

Jonathan

Comments

  • kwinnkwinn Posts: 8,697
    edited 2014-12-21 20:13
    I'm wondering why you need so many valves for a hot tub. Can you post a piping diagram of what you have in mind?

    I have worked on Honeywell and Siemens zone valve actuators with proportional controllers. They are powered by 24VAC and are controlled by a 0 to 10V analog signal. Is this what you have in mind, or do you want only open/closed or multi-position type valves?
  • JonathanJonathan Posts: 1,023
    edited 2014-12-21 20:59
    Well, it is going to be an interesting plumbing situation. I am going to have a 50 gallon hot water tank as well as the tub. When the tub is hot, the solar heater will switch over to heating the 50 gallon tank up to around 180 degrees. Then at night or in the morning (I love a tub with coffee) dump the extra hot water into the tub to maintain temp.

    So I need simple open/close type valves. Two straight through and two "wye" types, they may call them diverters? This will allow me to switch between heating the tub and the tank. I also have a wood burning heater (a Chofu) in the system and may even bring in an antique 1930's sidearm heater that I restored.

    Jonathan
  • kwinnkwinn Posts: 8,697
    edited 2014-12-22 06:44
    Sounds like a fun project. I will see what I can find in my manuals and at the supplier I deal with later today.
  • JonathanJonathan Posts: 1,023
    edited 2014-12-22 09:27
    That would be great and much appreciated. I can seem to find many examples of DIY controllers for zone valves.

    J
  • kwinnkwinn Posts: 8,697
    edited 2014-12-22 14:25
    Don't have any useful info on zone valves left on my laptop. Must have deleted it after I left Honeywell. You can search the Honeywell web site for info, and also try Johnson controls and Siemens.

    Home Depot here in Canada carries 1/2 inch zone valves from Watts Water Technologies for $79.30. You might also be able to adapt regular plumbing valves or washing machine solenoid valves to do what you want. Two and three way valves are also available but they are pretty pricy.

    What sort of controller do you want for the valves, on/off or modulated?
  • JonathanJonathan Posts: 1,023
    edited 2014-12-22 15:43
    That is a pity. What I am looking for is just open/close, no need for any proportional vlaves. I'll be controlling it via a Propeller. It seems that most are 24vac, so i can use ss relays to actually open and close them.

    I'm not married to zone valves, but it seems as if they are a good fit although expensive. Being able to get parts to repair instead of replace is one of the aspects of the zone valves that I like, as well as the fact that they are rated for the.temps I am working with. Are some.easier to ctrol? Is there a brand you recommend?


    Many thanks for the help!

    Jonathan
  • kwinnkwinn Posts: 8,697
    edited 2014-12-22 20:15
    If it's just open/close you could use regular brass or plastic ball valves and either DC gear motors or continuous rotation servo motors to open/close them. I used 1/2 inch plastic ball valves and auto window motors for a small greenhouse automation project. Not sure if the plastic valves would work on hot water, but they do use plastic solenoid valves for hot and cold water on washing machines.
  • MJBMJB Posts: 1,235
    edited 2014-12-23 02:23
    Hi Jonathan,
    I am in the planning and building a solar heating / pool system for our house in Spain as well.
    Regarding a zoned storage and it's loading preserving the thermal layers, there is an alternative to the usual zone valves.
    It comes from passive solar systems.
    To preserve the thermal layers it is important to feed at the level with - more or less - the same temperature as the feed
    to not create thermal currents that mix up the layers.
    This can be done with an external 'feed-pipe' this is a relatively thick (5 to 10 times the area of the pipe) vertical pipe,
    that has a many connections to the storage tank as you have available.
    The hot pipe is connected to the middle of the 'feed-pipe' so the water can 'decide' by gravity at which level it 'wants' to flow into the tank.
    The outlet back to the collectors is taken from the bottom of the storage tank.
    Buffertank.jpg

    no valves, no sensors, no controller, no extra energy ... just let nature do it's work
    AND - you want to run the pump at low volume flow - otherwise you will mix as well.
  • Mark MaraMark Mara Posts: 64
    edited 2014-12-23 06:16
    I have been using a C3 to control the zone valves on my heating system for a couple of years. I am using AQY212GH PhotoMOS relays. The PhotoMOS relays are rated at 60 V AC/DC 1.1 A. These relays come in a 4-pin DIP package. They work great to control 24 V zone valves. There are probably better solutions, but this has worked for me with no problems.

    --markM
  • JonathanJonathan Posts: 1,023
    edited 2014-12-23 07:50
    @Kwinn - I have made my own motorized/servo valves in the past and the failure/issue rate has been too high.I admit it is more of an issue of my skills but for this one I think I want "real" valves. Plastic valves aren;t for me, for one thing the temp of the storage tank might be as hot as 180F.

    @MJB- I am past the point where I could go for thermal siphon, although I see the beauty and my wood burning heater uses a thermosiphon. However, the tub is already located 10 feet below the solar thermal. I have also located the storage tank. So pump it is.

    @Mark- Thanks! The relays you mention look great and great price. What is a C3 controller? I want to use a Propeller.

    Thanks for all the replies!

    Jonathan
  • PublisonPublison Posts: 12,366
    edited 2014-12-23 07:58
    Mark may be refering to the Propeller C3 board:

    http://www.parallax.com/product/32209
  • Mark MaraMark Mara Posts: 64
    edited 2014-12-23 08:00
    A C3 is a Propeller based credit card sized computer. Parallax has them on sale http://parallax.com/product/32209. I added a daughter board for a real time clock, the relays, terminals, etc.

    --markM
  • MJBMJB Posts: 1,235
    edited 2014-12-23 08:59
    Jonathan wrote: »
    @MJB- I am past the point where I could go for thermal siphon, although I see the beauty and my wood burning heater uses a thermosiphon. However, the tub is already located 10 feet below the solar thermal. I have also located the storage tank. So pump it is.
    Jonathan
    this is NOT about thermosyphon.
    You use a pump to feed the hot water into the storage tank.
    But you use gravity to let the water find it's way into the tank at the perfectly right level.
    This saves the zone valves, sensors, controller, power ...
  • kwinnkwinn Posts: 8,697
    edited 2014-12-23 11:42
    Jonathan, there are a lot of different types of zone valves and actuators available. Actuators from one manufacturer will not necessarily fit or work with the valves from another. My suggestion would be to look for a local distributor or order over the internet once you have decided on what you want.

    I think this one would be suitable for part of your system:

    http://www.globalindustrial.ca/p/hvac/pumps-circulators/hydronic-valves-accessories/honeywell-24v-low-voltage-motorized-zone-valves-35-capacity?infoParam.campaignId=T9F&gclid=CMDzltLq3MICFasRMwodPVUA2Q

    Another thing you need to do is to draw a diagram of the entire system with the location and type of zone valve. Building automation systems generally use normally open valves in cold climates so that heat stays on if the control system should fail. You will need to decide where you want the valve open in case of failure, and where you may want it closed.
  • kwinnkwinn Posts: 8,697
    edited 2014-12-23 11:49
    BTW, several of the propeller boards would be a good choice as the controller for the system and the AQY212GH PhotoMOS relays would be good for powering the valves. Thanks for posting that info Mark.
  • JonathanJonathan Posts: 1,023
    edited 2014-12-23 13:48
    @MJB- I think my system will need sensors. I'm very curious about what you are saying though, any links or more information?

    @mark- Thanks! That valve is one of the ones I have been looking at. I have made my diagram and know that I need two wye valves and two straight through's. I do have the NO/NC situation figured out. This system will be partially a drain-back, so the NO side of the wyes will be oriented for this.

    As for controllers, I will be using a Prop/Xbee combo, I am working on modifying a PCB layout and hope to have the boards in a few weeks.

    Many thanks for the help folks!!

    Jonathan
  • JonathanJonathan Posts: 1,023
    edited 2014-12-23 14:13
    Mark, looking through the valve information I saw this:

    Use this valve in closed loop hydronic systems that do not contain dissolved oxygen in system water, such as fresh water from frequent source of makeup water. Valve designed for cycling (not constantly powered on) applications.

    Why is this? And a hot tub does not seem to fit that description.

    Thanks!

    Jonathan
  • kwinnkwinn Posts: 8,697
    edited 2014-12-23 20:05
    Jonathan wrote: »
    Mark, looking through the valve information I saw this:

    Use this valve in closed loop hydronic systems that do not contain dissolved oxygen in system water, such as fresh water from frequent source of makeup water. Valve designed for cycling (not constantly powered on) applications.

    Why is this? And a hot tub does not seem to fit that description.

    Thanks!

    Jonathan

    No, a hot tub does not fit that description. Oxygen in the water promotes corrosion. Most heating systems are closed loop and only add small amounts of water to make up for losses, and may have anti-corrosion additives. Can you post a piping diagram of the system?
  • JonathanJonathan Posts: 1,023
    edited 2014-12-23 20:42
    I'm at work on a 48 hour shift. When I get home I can try to draw something.

    The thing now is finding valves that will be OK. My guess is that those valves would probably be fine. In a hot tub the combination of hot water and bromine is always hard on copper but brass seems to do pretty well. In my experience with hillbilly hot tubs, copper lasts for a number of years but does run into problems. Brass seems to do fine. I have very low bromine levels and hope to switch to ozone. In any case, stainless valves are beyond my means. Plastic is attractive in some ways, but the 50 gallon storage tank is going to run pretty hot.

    Jonathan

    OOps, just saw I've been mixing up Mark and Kwinn. Sorry guys
  • MJBMJB Posts: 1,235
    edited 2014-12-23 23:51
    Jonathan wrote: »
    @MJB- I think my system will need sensors. I'm very curious about what you are saying though, any links or more information?
    yes - of course, for the rest of the system you will need sensors.
    Or you WANT sensors ;-) - to document everything on SD and display it on the web-site set up with Peter's IoT5500 ;-) ...
    I will place at least 6 or 8 sensors on the storage tank to get a 'picture' of the temperature distribution.
    To check that the tank is really layered and not stirred up accidentally.
    8 will make a nice 8x8 LED-Matrix display .

    as for link - I picked it up on some german solar DIY sites and all using it are happy with it.
    And if you just think it thru it is actually very simple.
    The external vertical pipe with wide diameter gives a slow vertical current that will feed automatically at the correct level
    into the tank. And the vertical currents are outside of the tank so the tank is not mixed up.
    The temperature layers are untouched and stable.
    It requires a little more 'passive' HW but you save the 'transistors'.
    For my tank I will get a custom welded feed-pipe (might not be much cheaper than the zone-valves unless you have somebody doing it cheap or you can do the welding yourself)
    The fat pipe I picked up at the scrap yard. - and of course it needs to be insulated as well.
    Since I will be using under floor heating I will have very low return flow temperatures which makes best use of the stored energy
    when the tank is NOT mixed up. And the top is still nice hot.
  • kwinnkwinn Posts: 8,697
    edited 2014-12-24 08:59
    Jonathan wrote: »
    I'm at work on a 48 hour shift. When I get home I can try to draw something.

    The thing now is finding valves that will be OK. My guess is that those valves would probably be fine. In a hot tub the combination of hot water and bromine is always hard on copper but brass seems to do pretty well. In my experience with hillbilly hot tubs, copper lasts for a number of years but does run into problems. Brass seems to do fine. I have very low bromine levels and hope to switch to ozone. In any case, stainless valves are beyond my means. Plastic is attractive in some ways, but the 50 gallon storage tank is going to run pretty hot.

    Jonathan

    I also think that brass zone valves would be ok, particularly in the heating/storage tank portion of the system. The hot tub water will be much cooler (95-106F? I found 105F to be the max I could handle.) so plastic zone valves would work there if they are available. This is why I wanted to see a diagram of the system. It might even be possible to adapt standard plastic valves to the same actuator as the brass valves.

    Not sure ozone is an improvement over bromine though, OO2 is even more reactive than O2. If the hot tub water is isolated from the heating system by only dumping water in to the hot tub or using a heat exchange coil you could use plastic valves.
    OOps, just saw I've been mixing up Mark and Kwinn. Sorry guys

    No problem, that's what I thought.
  • JonathanJonathan Posts: 1,023
    edited 2015-01-08 10:39
    So, I got the PCB's I had made and they work fine. Now I need to design the output board. I'm thinking of using these SSR's, they are cheaper than the ones linked earlier in the thread and can source much more current. If I'm reading it right, a 1k resistor to Prop pin should drive these, right? And these are also zero-crossing, which is nice too.

    http://www.clare.com/home/pdfs.nsf/0/8471676520A90EC185256F5600507F99/$file/CPC1976.pdf

    What do ya think?

    Jonathan
  • kwinnkwinn Posts: 8,697
    edited 2015-01-08 20:08
    Those SSR's are good for AC powered zone valves and the prop pins can drive them with only a current limiting resistor in series with the led input. Can also work with DC zone valves by using AC power and a bridge rectifier for the output.
  • JonathanJonathan Posts: 1,023
    edited 2015-01-29 09:51
    I was getting ready to order some of the relays I linked above when looking through the data sheet I noticed that under the output specs it shows a minimum current of .7 amps. Does this mean that the relay WON'T run a load less than that? If so, these won't be any good for zone valves.

    Thanks!

    JOnathan
  • kwinnkwinn Posts: 8,697
    edited 2015-01-29 20:46
    Those are intended for AC use and have a minimum of 75mA (.075A) holding current. That means they will stop conducting when the load current drops below 75mA unless the opto leds are on. They should be fine for this application.
  • JonathanJonathan Posts: 1,023
    edited 2015-01-29 21:09
    Kwinn,

    Oops. Dropped a zero. .07, not .7 amps. Duh. Thanks for the help, just added some to my cart.

    JOnathan
  • JonathanJonathan Posts: 1,023
    edited 2015-01-30 08:12
    Kwinn,

    So, another question: I am designing a board for the relays and was wondering if I should put a weak pulldown, say 100k, to keep the relays off when powering up?

    Thanks so much for all of your help. Really.

    Jonathan
  • kwinnkwinn Posts: 8,697
    edited 2015-01-30 20:44
    Jonathan wrote: »
    Kwinn,

    So, another question: I am designing a board for the relays and was wondering if I should put a weak pulldown, say 100k, to keep the relays off when powering up?

    Thanks so much for all of your help. Really.

    Jonathan

    Not really necessary. The leds require quite a bit of current to turn the output on. Propeller pins as inputs (floating) provide virtually zero current, and the uln2803a already has pulldown resistors on chip.

    PS You're posting questions in this and the propeller forum on the same topic and it's causing a bit of confusion
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