Please Help, Have Problem With Solar Hot Water Heater

BCConstruction

im asking about the system is because if the system dont have a exspansion vessel water under pressure can be superheated way above 100c and to levels as much as 150c depending on size and type of panels. This can cause the water flowing around the coil to super heat the water in the cylinder way above what the cylinder stat would allow thous opening the PRV. Now normally the pump control unit would normally bypass the cylinder and allow the water to cool a little but even when the pump shuts down system can flow by gravity without even a pump running. just like gravity heating systems. If he has changed the PRV and it's still doing it then it would seem as if there''s still a pressure or heat problem somewhere in the system. If the electric system aint running then it has to be the solar system. I have also seen this happen when a coil goes bad and leaks into the hot water cylinder and pressure increases beyond the PRV but then you would notice a drop in your Solar system pressure.

But it would could be something as simple as the wrong PRV!

BCConstruction

Yeah take a picture. Be a lot easier to see what system you have.

bwalley

You can type a bunch of words, but based on the last sentence you have no clue waht you are talking about.

It is a water heater, therefore it is required to have a Temperature and pressure relief valve.

Maybe you should go take some pictures of other peoples boats and post them.

maleko

How do i tell if its a closed system or a open system. this way i can look when i go by later today. Sorry my post will be a little late since im 6 hours behind most of you... but ill post the pics.. Thanks...

BCConstruction

Lol call it want you want. TPRV/PRV/PR/PV

Yeah i just get my wife to lay on top of peoples boats so i can take pictures and get into them and take pictures of the dash. Sometimes i even steal it for a few hours and use it and take photos of me on the back.

Jealousy gets ya no where fella ohh yeah i also have a massive Peni$.

BCConstruction

Well sealed/closed system should have a expansion vessel. They might make one without one but i have never seen one so don't quote me on that. Open vent means that the system will use a vent for expansion and the pipe will normally be high enough above the pump so that the pump cant pump over when running. Hard to explain. Let me find a picture.





Ignore the vent at the top of the 2nd pic as that just an AAV so that air can be bleed from the system.

bwalley

I am not jealous of you, I do not envy anyone, I am happy with what I have.

BTW do you have a contractors license, or do you just rely on your "mates" pulling the permits?

bwalley

Wrong again, the more you type, the more you show your ignorance about solar systems.

The vent on an open system is to allow air to escape from the system, otherwise it can get an airlock and it will not be able to circulate water.

The collector will have a pressure relief valve on it, in case it has been isolated from the storage tank and it develops too much pressure it can safely release it.

the storage tank or water heater, will have a T&P relief valve, it does not need an air vent.

maleko

the valve i used to replace the bad one is a T&P Valve 5/8 shank 150psi setting / 210 degree temp. 3/4 outlet 3/4 inlet

BCConstruction

errr yes i do have a contractors liscense thanks. It's only a c but that all i need at the moment. Aint doing big jobs.

If you would ever plumb in a open vented system you would know that when a system over heats/boils up the extra water will come out of the open vent. Thats the reason your ment to leave an air gap between the high water level and the open vent other wise is causes a syphon and the water flows around the header tank.

Dam man i lernt this after the first week.



But what you say about the vent being used for air is also correct but it's not an air lock problems he having.

BCConstruction

Yep thats the correct valve for sea level.

Just double checked and it is ok for sea level pressure of 14.7 psi or below. I have never had to fit a different rated one but it's always worth double checking.

naptown CR

There is a very good possibility that in Hawaii this is not a closed loop glycol or even a drain back system
Could be a direct transfer. similar to a thermosiphon system but with a pump.
The valve he described is in the storage tank not the storage loop.
It is very possible that he has a controller that is not shutting the system down and allowing the temp to build in the tank.
Pressure should not be an issue on the storage tank unless
A if on a well the pressure tank is saturated and is not allowing for expansion
B if on city water there is a pressure reducer or check valve on the inlet to the house.

naptown CR

Interesting thread just bumping it

naptown CR

Let me know whaqt you saw there today
I am trying to keep this bumped up so there are some useless posts.
If you have pictures of the system I can perhaps help without calling you an incopetent as some here have.
We need to set up a diagnostic tree to determine the problem
PM me if you wish

maleko

Thanks naptown, im just waiting for the owner to get home so i can go by and take pics and look a little deeper. i will post as soon a i can, thanks to all for you input. im sure between all of you we will figure it out.
im going to put a pressure gauge on it when i go over there today, on th einlet side and on the outlet side, what should be the rec. pressure there?

Tom Struble

naptown chompin at the bit

__________________
Tom

naptown CR

you know what I do

and yes helping a bro out (particularly one 6 thousand miles away and not competing directly) is satisfying.

Berating someone is not my style anymore!

Tom Struble

your the man
i like your style

__________________
Tom

bwalley

It is not a thermo siphon or a passive system since it has a pump, it is an active system The pump is the give away.

On the type of system he has since it is most likely an open system, there is no "storage loop" the water heater is the storage tank.

If there was a problem with pressure in the house, he would have other problems such as the water closet fill valves not closing, as well as problems with the faucets and the HO shoud have noticed unusually high pressure.

The pressure tank on a well is to keep the well pump from short cycling and would not cause the problem he is describing.

I explained to the guy about the high limit on the controller either being turned off or not working, that will cause high temperature, also if it is a PV pump system, it will not have a high limit.

naptown CR

This could very well be a direct loop where potable water is pumped through the colectors.
I never said it was a thermosiphon or passive system read the post I indicated that there was a pump

there was no indication in any of the posts that there was unusual pressure not to say that there was not but this was not indicated.

If they are on a well and the pressure tank was saturated meaning that the air space was no longer there this could also cause a t&p valve to relieve. remember that there are check valves in most well systems either at the well pump if a submersible or at befor the pressure tank if a jet pump. Without a check valve the pressure tank would immediatly push the water back down the well. If the bladder has gone in the pressure tank and the tank is saturated there is no place for the water to expand and therefore will pop the t&p valve.
On municipal system it typically expands back into the water main.

Highlighted in red in your post is dead wrong. I am ashamed of you. You passed the plumbing masters test on the first try?
Must have failed physics 101 or have not ever worked on a well system.

BTW even a PV pump should have a high limit cut out. I always install one.