Please Help, Have Problem With Solar Hot Water Heater

maleko

I am not a plumber, but im having trouble with a clients solar hot water heater. the actual hot water heater keeps blowing the relief valve. it is attached to the the solar panel and is only there to come on if the temp dips below a certian temp. it also has a recuclatory pump. (spelled wrong) i replaced the pressure relief valve because it would open and would not shut on its own. i installed a new one and it worked like a charm for 2 days then it keeps reliefing itself, too much pressure.. from where??/ im confused, do i need a expansion tank maybe? why would there be to much pressure in the system? shouldnt there be a relief vave up on the roof attached to the solar panel? i havent been up there to look yet but will this weekend... what is my next step, besides calling a plumber...
thanks for any advice.....

matt700

not a plumber just speculating. you could have a restriction in the circulating system. Haven't dealt with solar heaters at all, but you may have a problem with the t-stat. might be getting an overpressure from excessive heat. again- no experience with solar water heaters, but, unless i am missing something i can't imagine a need for a "pop-off" at the solar panels. is the pump new? what size suction and discharge lines does it require? unless the pump has been there all along i would compare the pump output to the rating to the relief valve. might have excessive pressure from the pump if the lines are the wrong size. hope that helps. sorry if i sound like an idiot. good luck

BCConstruction

All the solar hot water system i have fitted have had a expansion vessel of some kind. It should really have one unless it works on an open vent system which i have never seen. Whats more than likely happening is your mains pressure is keeping the hot water cylinder at 4bar for example and when the solar heat kicks in it will heat that water and expand and needs somewhere to go. The only way out is the taps or the PRV as there's probably a check valve in the system so it cant expand back into the mains. Also depending on what system they had installed some of them can reach some unreal temps in direct sunlight and if the stat is set to something over 60c then you can have problems. I seen some set as high as 80-90c before . Thats a lot of expansion.

maleko

Thanks for the feed back guys... im thinking its getting way to hot. we live in Hawaii and the sun is blazing here all day every day. So maybe the T-Stat is set to high? not allowing the water to circulate? i will order a expansion tank, this gets installed between the panels and the hot water tank as close to the tank as possible, correct? there hot water tank is electric and they keep it turned off at the breaker cause the solar water is always hot, so its just acting as the storage tank. any other thoughts.
Thanks again for your time...

bwalley

Do your client a favor and have them call either a Licensed Solar Company or a Licensed Plumber that has knowledge about solar water heaters, it is obvious you guys are in over your head.

It is an easy fix, IF you know what you are doing.

Why is a carpenter working on a solar water heater?

The funny part is a handyman who gave advice, doesn't know what he is talking about.

BCConstruction

Yep just make sure you get a correct size liter expansion tank to suit the size of the system. They are very easy to fit and you just T them of right after the filling loop and check valve. Instructions should give you a detailed diagram of where to install. You also have to make sure the expansion vessel is charge with the correct psi of air. This should also be in the instructions. You can use a normal bike pump and a pressure gauge. Once that is installed then check the system stat and make sure it's no higher than 65c and you shouldnt have any problem. Make sure you have a gauge on the Expansion vessel as you will need to know what pressure your charging the system back utpo. All this stuff only counts though if it's a sealed system and not vented.

BCConstruction

Of course i dont. I have only fitted 50+ dual coil solar heating system.

bwalley

It is obvious you don't have a license.

It is also obvious you don't know what you are talking about because you gave the wrong advice.

BCConstruction

Yeah it's really Obvious. You clearly ain't got the first clue about plumbing my man. Now move along troll unless you have some information that will help the man.

BCConstruction

Dont know if this digram will help you but it shows you the layout. There are many systems though so not all will be laid out like this.

bwalley

I have installed close to 2 thousand solar systems, (domestic water heaters and pool systems) and have built hundreds of pool systems.

I passed the State of Florida Plumbing contractors exam (which icludes solar heaters) on the 1st attempt (only about 32% of people taking it do it on the 1st attempt) I am also a certified Building contractor and a Certified Air conditioning contractor.

What credentials or licenses do you have?

I thought you mentioned something about having to deal with green cards and work visas and that was why you weren't licensed, but i could be wrong.

It is obvious you have no clue what you are talking about in regards to solar water heaters.

BCConstruction

Well come on then pro. What his problem! Your the expert so you should be able to tell him.

maleko

ok lets stay on topic please..
bwalley. why is a carpenter working on a solar heating system.? because i want to. i know the Basic's of plumbing and have done some hot water heater installs before, its really not hard. ive just never worked with a solar system before, this is why im asking questions... You see i know your answer is call A professional....everyone is quick to say that, So you mean what ever your trade is.. you have never done other stuff yourself, youve never fixed a outlet or a leaky pipe? i find that hard to believe, but if you did, u should have called a professional... BUt you see bwalley i live in Hawaii, on a small island, where there is only 1 plumber, and doesnt know anything.. so here we do what we can without having to fly in plumbers, electricians etc . from the mainland. we try to be very universal when we can... im a licensed contractor and a finish carpenter by trade, but i can wire a house and plumb a house too, and have gotten signed off by building inspectors all good.. ive just never worked on a solar heater system... so im here looking for advice to see if i can solve the problem myself...

davitk

I skipped the pissing match so it may have been mentioned there..... but isn't what you are calling a pressure relief valve actually a temperature-pressure relief valve (TPRV)?

maleko

i believe so.. it is what was ontop of the electric hot water heater, not a storage tank.

bwalley

The system you showed him is a closed loop system, not typically installed in hot weather climates such as Hawaii.

He said it was the pressure relief valve on storage tank, in the diagram you showed, the expansion tank is not in the plumbing for the storage tank, so how could that be what the problem is?

The tank should have a T&P relief valve, if that is going off, it is either due to temperature or pressure.

If the high limit is turned off or not working on a controller system, the storage tank temp. can get too hot, causing it to go off on temeperature, the same thing can happen if it is a PV system, the typical PV system does not have a high limit, it will circulate the water and continually heat it as long as there is enough sun to generate electricity, there is enough sun to heat water.

He needs to take the temperature of the water in the storage tank to see if it is temperature setting offf the T&P relief valve.

He may not have installed the proper T&P relief valve, when he changed it out, that could be why it is going off again.

Wter heaters are required to have a T&P relief valve, while the collectors will have a pressure relief valve only, they also need an air vent, and the system will need some form of freeze protection, usually an FP45 will be used.

BTW What contractor licenses do you have?

maleko

as far as i can see there is no storage tank.. just the electric hot water heater tank. that i assume is doubled as a storage tank? that is the valve that keeps blowing the one ontop of the hot water heater.. does this help?

bwalley

The water heater is the storage tank, I explained it in detail in the PM.

take the temperature of the water in the storage tank, that will help you figure out if it is pressure related or temperature related.

it sounds like you have a defective T&P valve.

BCConstruction

Maleko do you have something like this connected to your hot water cylinder? It may have a cover over it so may not look exactly like that. you see the Exspansion vessel inside. This means you have a sealed system dual coil cylinder. If you do we will go from there. You could have done something silly like put the wrong PRV in but i guess your head is screwed on a bit better than that.

maleko

WHOA..... Nothing looks like that at all. i will take a pic later today and post what im dealing with.. Thanks for all the input