Looking to replace solar water heater

[ardcarmvk]

So this morning I did not manually turn on the pump, I will be home tomorrow afternoon to try it out. But today when I got home the top of the tank was at 97 deg and bottom was at 87 deg. The way I disconnected the lower element must be wrong. Once I re-hooked up the lower element the heater is kicking on again. Reading the diagram it looks like it would be okay but obviously it is not.

On page 2 of 2 I disconnected the two leads to the element red and black. In this mode it was not working. I measured votage from L1 to L2, L1 to L4 and L1 to T2 and I got 250V on all of them.

I now have lower element hooked up. So other than energy savings is there any benefit to disconnecting the lower element. I am okay with leaving it connected and having both elements as a solar back up. Thoughts?

238-47104-00A_pg6-7.pdf

[MikeSolar]

So here's the update on progress and pit falls. I finished all the hook up over the weekend per specs. I have 10k thermistor wedged in between insulation and tank. I am getting about 4.9k ohms so I have 107 degrees in my tank @ 4pm when I got home from work. =( I checked resistance on the collector sensor and it is infinite resistance. Don't think that I broke that when I was installing. Thing I don't understand is I know I saw it and heard it cycle on and off before my retro fit.

I switched the pump on for ten minutes and measured temp at top glycol side of heat exchanger under insulation and got 105 degrees. Same time I measured, Phoenix peaked 104 degrees air temp @ 4pm sun not crazy hot but no clouds. I really expected a bunch more just residual in the lines giving even if it did not pump during the day. Before retro fit I was getting 120 deg with both elements.

What I am planning on tomorrow I can turn the pump on manually from 7a - 5p and see what temp I get while I am off at work. If it is good I will just get a new thermistor for the collector. If not I wonder if I have a bubble in the glycol side or something. I have 10 psi and I should have about 25 psi from what I heard. I HOPE this works it would suck if I went through all this to have more wrong with my system.

10psi is defo a bit low. A ranch house can deal with 15psi of it doesn't get too cold in the winter. 25 is what I usually charge to. Infinite resistance is not good. Hopefully there was no lightning issues.

[ardcarmvk]

So here's the update on progress and pit falls. I finished all the hook up over the weekend per specs. I have 10k thermistor wedged in between insulation and tank. I am getting about 4.9k ohms so I have 107 degrees in my tank @ 4pm when I got home from work. =( I checked resistance on the collector sensor and it is infinite resistance. Don't think that I broke that when I was installing. Thing I don't understand is I know I saw it and heard it cycle on and off before my retro fit.

I switched the pump on for ten minutes and measured temp at top glycol side of heat exchanger under insulation and got 105 degrees. Same time I measured, Phoenix peaked 104 degrees air temp @ 4pm sun not crazy hot but no clouds. I really expected a bunch more just residual in the lines giving even if it did not pump during the day. Before retro fit I was getting 120 deg with both elements.

What I am planning on tomorrow I can turn the pump on manually from 7a - 5p and see what temp I get while I am off at work. If it is good I will just get a new thermistor for the collector. If not I wonder if I have a bubble in the glycol side or something. I have 10 psi and I should have about 25 psi from what I heard. I HOPE this works it would suck if I went through all this to have more wrong with my system.

[ardcarmvk]

Okay had problems taking out the dip tube... worked way too much on this this weekend. I had to replace all copper and mixing valve. Learned that my solder skills are poor but I got better. I have tank temporarily set up as non solar but still with mixing valve and will try to continue next weekend taking out the dip tube with the pipe wrench. It will give me time to get a thermistor. But I did take a nice hot shower with full water pressure now that I have new pipes. =)

Thanks for all of your generous help.

[MikeSolar]

HA! funny thing too I finally see my "thermistor" setup on my old tank that was I imagine professionally installed. I found the end of the wire from the bottom access panel one side had a wire nut on it and the other side was exposed. making it an open circuit. So I imagine it would be always on? But I know that the pump did cycle on and off. Now I am not sure but will see if I can pick up a 10k thermisor at lowe's or something it is sunday might be hard to find.

I doubt you will find one at Lowes but try "Digikey". You can buy it online. Start at this manufacturers website. http://www.cantherm.com/products/thermistors/index.html

[ardcarmvk]

HA! funny thing too I finally see my "thermistor" setup on my old tank that was I imagine professionally installed. I found the end of the wire from the bottom access panel one side had a wire nut on it and the other side was exposed. making it an open circuit. So I imagine it would be always on? But I know that the pump did cycle on and off. Now I am not sure but will see if I can pick up a 10k thermisor at lowe's or something it is sunday might be hard to find.

[ardcarmvk]

Don't connect to the lower element. Place it in close contact with the tank vessel and insulate over it well. Then wire it to the controller.
Your controller may have a function that will keep the tank element (upper is all that should be operating in this instance) from coming on if the bottom of the tank is warm and the solar is generating heat. Check the documentation that came with the controller or go on line and find out.

Okay I have this figured out a bit more. I learned that the sensor is a 10k thermistor and I think I will wedge it between the tank and the insulation near the bottom of the tank in the element access panel. Usually it is bolted somehow to the tank but i don't know how that happens with out losing pressure and integrity. I found an article once again in homepower mag that gives a chart with ohm to temperature values for the thermistor so I can see if my temperature is getting read accurately with it just next to the tank.
That article is here: http://homepower.com/article/?file=HP103_pg60_Marken

[Naptown]

there are two sensors one to the collector and one for the tank. I do see the merit in hooking it up to the element without power. =) I will dig and investigate more to see how the old one works.

Don't connect to the lower element. Place it in close contact with the tank vessel and insulate over it well. Then wire it to the controller.
Your controller may have a function that will keep the tank element (upper is all that should be operating in this instance) from coming on if the bottom of the tank is warm and the solar is generating heat. Check the documentation that came with the controller or go on line and find out.

[ardcarmvk]

No you can't hook up the sensor to the element if that is what you are thinking.
Are there 2 or three sensors for the controller
If only two put the tank sensor in the area where the lower element is after you disconnect the lower element. Unless there are three sensors you only use the one in the collector and one near the bottom of the tank.

there are two sensors one to the collector and one for the tank. I do see the merit in hooking it up to the element without power. =) I will dig and investigate more to see how the old one works.

[Naptown]

No you can't hook up the sensor to the element if that is what you are thinking.
Are there 2 or three sensors for the controller
If only two put the tank sensor in the area where the lower element is after you disconnect the lower element. Unless there are three sensors you only use the one in the collector and one near the bottom of the tank.

[ardcarmvk]

The interlock is probably controlling the element in the tank.
How many sensors? and where did they come from on the old tank?
Put them back in the same relative positions on the new tank.
And don't forget to disable the bottom element by disconnecting at the top thermostat.

Two sensors one to the collector that is a-ok untouched. The other is to the tank.
The sensor had a hole to go into on the top of the old Solar tank with nice grommet etc. I do not have a sensor location that I could see on the new tank. Can I cut the wires and hook it up to the thermostat by the top element? Pics and diagram below.

Old tank red wire on to right.


New tank fit to thermostat??




Well I also found the reason for my low water pressure hot out was filled with black corrosion bit more than a pencil tip in thickness surprised that I got as much water as i did.

[Naptown]

The interlock is probably controlling the element in the tank.
How many sensors? and where did they come from on the old tank?
Put them back in the same relative positions on the new tank.
And don't forget to disable the bottom element by disconnecting at the top thermostat.

[ardcarmvk]

.....
Sensors may require a bit o finagling to get them in the correct position. perhaps even cutting through the Jacket of the water heater at the top and inserting and reinsulating around it.
What controller do you have (resol?)

HELP!!!! I am ready to do the install but I do not see where to put the tank sensor for my differential. Prompt help would be appreciated.
Thanks -Andrew

[ardcarmvk]

Don't change the High limit on the controller. I anything run it up to 140. you need to leave a bit of wiggle room on the high limit. 200 will not allow any room for stagnation and cooling when load is low.
Mixing valve should remain in the same relative position as it was on the outlet of the tank.
Sensors may require a bit o finagling to get them in the correct position. perhaps even cutting through the Jacket of the water heater at the top and inserting and reinsulating around it.
What controller do you have (resol?)

Naptown, I have a old gold line gl-30 it has an extra dial "element interlock" that I do not know what it is. Interlock was the one that was @ 130 degrees. I have my high limit @ 170. Pics below.

So when you say cutting through the jacket of the heater that is the R-8 insulation that I am going to buy and not the 2" of heater insulation right? I am still having a problem seeing how the sensor installs.

[ardcarmvk]

I would change the glycol for sure. After 17 years, the reason it MIGHT be ok is that you had a big tank but the longest I have ever waited to change someones glycol is 10 years and it was pretty yucky. Unless I am blind, I don't see an expansion tank either.

If it is not too late, Bradford white has an 80gal tank with an electric element in the top and a heat exchanger in the bottom. You could get rid of your back up tank.

Yeah I already bought the 50 gallon according to the article for arizona and 24 sq ft x 2 gallons, 50 gallon should be okay. I don't have a back up tank just the one that I bought.