Expansion Tank Tee

[Jadnashua]

And, it also says that higher pressures than 80psi are dangerous. The WH is typically tested to 300psi, but the safety relief valve is set to 150psi to provide a safety margin.

Pre-charge is used to essentially put the bladder in its neutral position when 'normal' pressure is in the lines. It also allows the maximum safe volume when the water is heated.

Bottom line, install per code which also means following the device's installation instructions. If you look at the typical installation diagrams in any of them, they do not show a valve between the ET and the WH.

 

[Reach4]

And, it also says that higher pressures than 80psi are dangerous.

No, it doesn't. Where do you get this stuff, if you don't just make it up?

 

[Sponsor]

 

[Jadnashua]

"Do not exceed 80psi (5.5 bar) air charge. Air charge pressure exceeding 80psi (5.5 bar) could become hazardous and will void any and all warranties, either written or implied. Failure to follow these instructions will result in the possibility of property damage, serious bodily injury or death."

It seems quite plain and straightforward to me...

 

[go_hercules]

Original poster back here: after following this discussion, I decided I would put in three 5 gallon tanks in parallel and charge them to 1500 psi. Since my air compressor doesn't go that high, I will use acetylene since I have a bottle of that I keep right next to the water heater. I figure if it blows up, then my warranty might be void, but at least I can have a really hot shower. I asked the people over at Home Depot and they said they thought that should work just fine.

 

[Reach4]

It seems quite plain and straightforward to me...

It appears that your "it" was for your Watts document, rather than the Therm-X-document I had quoted in #20. I note that you did not quote the "This Expansion Tank is designed and intended for water storage at a maximum pressure of 150psi" from your Watts document to support your claim that "And, it also says that higher pressures than 80psi are dangerous. "

Now I know where you would go next... you are going to claim you were talking about precharge.... precharge was not the topic of this thread. It was the direction that you wanted to use to divert the topic.

 

[Reach4]

Original poster back here: after following this discussion, I decided I would put in three 5 gallon tanks in parallel and charge them to 1500 psi. Since my air compressor doesn't go that high, I will use acetylene since I have a bottle of that I keep right next to the water heater. I figure if it blows up, then my warranty might be void, but at least I can have a really hot shower. I asked the people over at Home Depot and they said they thought that should work just fine.

 

[Jadnashua]

The reason the 150psi is there is that is the point at which a properly working T&P valve discharges. This is consistent across both brands. 80psi is the maximum static pressure that should be in the tank as a precharge.

 

[Reach4]

The reason the 150psi is there is that is the point at which a properly working T&P valve discharges. This is consistent across both brands. 80psi is the maximum static pressure that should be in the tank as a precharge.

Are you conceding that these two statements were mis-statements?

1. "To meet the requirement, there should not be any valve of any type between the ET and the WH. "
2. "All of them also will void any warranty if the incoming pressure exceeds 80psi (the max allowed in a residential setting."

 

[Jadnashua]

If you have a valve between the WH and the ET, the WH will almost certainly vent at the T&P valve. That's the reason why none of the installation instructions show a valve there.

On the Amtrol installation document you posted...do you see any indication of a precharge of greater than 80psi? There's a reason for that, it is not supported. It also states that you should follow any local and/or national codes, and those limit pressure to 80psi. So, sometimes you need to read between the lines if it isn't stated explicitly.

Give Amtrol a call and ask them if they will warranty an ET if you precharge it to 150psi. Watts certainly spells out the reality of the situation, it's dangerous and will void their warranty. If you precharge your ET to 150psi, it is highly likely that the T&P valve will discharge, since it will essentially be up against its stops with almost no room for any expanded water to go.

If you look at Amtol's warranty document

http://www.amtrol.com/media/pdfs/warranty.pdf

it states that the product must be installed, operated, and maintained per instructions...150psi precharge, valve placement, both would qualify as installation errors.

 

[Reach4]

If you have a valve between the WH and the ET, the WH will almost certainly vent at the T&P valve. That's the reason why none of the installation instructions show a valve there.

They show a check valve. They say the TET goes after the check valve. They are smart fellas.

On the Amtrol installation document you posted...do you see any indication of a precharge of greater than 80psi? There's a reason for that, it is not supported. It also states that you should follow any local and/or national codes, and those limit pressure to 80psi. So, sometimes you need to read between the lines if it isn't stated explicitly.

Nor do I see mention of under 40... But wait. This thread is not about precharge. You are diverting again.

I presume you have you retreated from the 1. and 2. statements I cited on #28.

 

[Jadnashua]

1. No valve between the ET and the WH as shown on all ET installation instruction sets I've seen (can you show one that says you can put a valve between the ET and the WH?)..
2. Amtrol...must be installed, operated per installation instructions, or void warranty...Watts, do not exceed 80psi, installed per instructions which both show no valve between the ET and WH, void the warranty. National codes...wp not to exceed 80psi. Installing a valve between the ET and the WH will produce wp in excess of 80psi unless something is leaking while reheating the water and no use.

Your house, do what you want as long as it doesn't endanger others. Codes are designed to keep not only you but your family and the public or future owners of the property from dangers to either safety or property. You may not like them, but we do live in a land of laws. Don't put a valve between your ET and the WH so that the pressures stay within acceptable range. Keep your wp no higher than 80psi to prevent excess wear and tear on pressure vessels (your WH), hoses, valves, etc. and to do that, the ET must be able to do its job all of the time.

 

[go_hercules]

OP here again. I have seen some elbows somewhere that had little tabs with holes cast on so the elbow could be nailed or screwed to something. I think they were brass. What are these called? I could not find them by searching online. They seem like they would be handy for hanging something like an expansion tank.

 

[Reach4]

Drop ear elbow.

 

[JerryR]

Not a very good picture but it shows how you can install a tank without any support needed.

This also has a Honeywell mixing valve connected between hot and cold.

 

[FullySprinklered]

Thanks for stopping by, herc.

 

[go_hercules]

OP here again. After some of the suggestions here, I will be teeing just out of the water heater, rather than up at the wall valve. The unit is a Bradford White and the cold water nipple is very short, so short that only the threads are exposed above the sheet metal top cover. If I add the tee there and in tightening it, it tightens the existing nipple some more will that affect the water tightness between the water heater and existing nipple? I think that when I tighten the tee enough it will probably turn the existing nipple some. I don't really want to take that nipple out but if I should so that it and the added tee tighten together I will. The nipple was already installed on the water heater which is about 2 years old now so I don't know what type of dope they used on it from the factory.