Hot water tank

44mcallister

I have a 12 year old stainless steel superstor ultra indirect fired water heater. Every other day or so the hot water at the facets gets cold. I drain/bleed the tank and hot water comes out of the tank usually with air, my system tends to get airlocked, quite frequently. After the water starts running cold I stop and the tank will normally heat up again and I have hot water for another day. I have had 5 different techs look at the problem and none have fixed it to date. Any help or suggestions would be greatly appreciated

wogpa67

Are you closing the isolation valve above the circulator when you purge? Why is the valve for the domestic exp tank closed?

44mcallister

I do close the isolation valve above the circulator. That smaller expansion tank was added as a fix for the air in the system, It never worked and I have had numerous techs say it is a code violation and dangerous so it was closed soon after it was installed.

wogpa67

The smaller tank is for domestic water expansion. It looks like an st-8.
Is something leaking behind the boiler?

44mcallister

No leaks. I opened pressure relief on the hot water tank and got water everywhere.

Zman

The circulators pumping directly into the boiler's expansion tank is what is making air removal difficult.
I am assuming that the system has performed adequately for most of it's life?
The question is, how is the air getting in?
What is your system pressure?
Does the boilers relief valve drip or occasionally release?
Does it fluctuate when the temp goes up?
Has anything changed recently?
Carl

44mcallister

Thanks Carl,
I'm presently getting quotes to have the circulators moved to the supply side.
Yes the system has preformed well till now,always has had airlock issues, just really bad the past 2 seasons.
System pressure has been raised over the past 4 years from 18PSI to 25PSI to its current 40PSI. Was raised to 40PSI last year. I live in a 4 story townhouse with the boiler in the cellar, 1 duplex apartment over two 1 bedroom apartments.
The relief valve does occasionally release. It just started happening after a tech backed off the flow checks in an attempt to get more heat (hot water flow) to the upper zone, That was recently, past 2 weeks.
No flucuations that I have observed.
Biggest change is I have been purging the hot water and upper zone daily due to airlocks. The other 3 zones have been maintaining proper temperature without any air issues.
Boiler is presently set at 200 degrees was raised last year.
Thanks again,
Brian

wogpa67

The main reason you are purging is because your relief valve is blowing off adding fresh water and air to the system. That does not need to run at 200 degrees and the pressure is set to high.

wogpa67

Ideally pumping away is best, but they put pumps on the return for ever{and still do} and most times it works fine. I never do it that way.
You should have a 30 psi relief valve, and most tridicators are a bit off .

44mcallister

I'll get the boiler temp back to 180 and have the PSI lowered back to 25. This will address the relief valve but I'll still have the air lock issues that have been going on for years just not to the severity of the past 2 months.

wogpa67

What is the output of that boiler?

icesailor

44mcallister said:

I do close the isolation valve above the circulator. That smaller expansion tank was added as a fix for the air in the system, It never worked and I have had numerous techs say it is a code violation and dangerous so it was closed soon after it was installed.

Ask the tech's to show you where in the code it is a violation to install expansion control on a DHW system.

Chapter and verse.

44mcallister

Its A Weil Mclain EG 65 input is 250,000 output is 209,000. Hope that is right I looked it up in the owners manual. Thanks alot for the help.

44mcallister

Thanks icesalior I will. I just opened it back up definitely more confident in the advice I receive here.

icesailor

Is that SuperStor piped with 3/4" black pipe? It should have been 1". Copper is better because sometimes, the Black Pipe will plaque/rust up at the coil. There is a new circulator with the letters "HRT" embossed in the pump housing. Is that the Indirect pump? To try to solve a lack of hot domestic hot water? If that is a high head, high volume head, and it is pushing against an obstruction, it can be causing cavitation inside the pump.

Its hard to tell the complete problem from photos.

You have no idea how many installations there out there exactly like yours that work fine. If you do a complete re-pipe and move everything around, don't be surprised if it doesn't solve the problem.

It looks like the supply and return for the system out of the boiler and back is 1" IPS black pipe. You have a four story building? That seems a little light in the supply to my thinking. I think you have some piping issues around the boiler and they don't have to do with the location of the circulator.

If the supply and return to and from the system into the boiler is only 1", how many BTU's per hour can you jam through a 1" steel pipe without using hydraulic mining pumps?

And not get air from cavitation.

Zman

44mcallister said:

I'll get the boiler temp back to 180 and have the PSI lowered back to 25. This will address the relief valve but I'll still have the air lock issues that have been going on for years just not to the severity of the past 2 months.

I think that is a good plan.
The expansion tank needs to be precharged to the system pressure while isolated from the system.
Carl

44mcallister

Thanks icesailor. That's something I will bring up to the tech this week. What you say makes a lot more sense then what has been done by them thus far.

44mcallister

Icesailor The black pipe for the return and supply pipe is 1". The pipes from the water heater measured 1 1/4". I have a back up circulator of my own and will swap it out with the HRT one, that was a recent suggestion and tech upgrade to address the air locking. Thanks for the advise.

icesailor

We don't measure by circumference, but the piping to the Indirect sounds like 3/4" and the boiler piping is 1". Do by the diameter. 3/4" is slightly over 1", and 1" is about 1 3/8".

44mcallister

Thanks I saw I got it wrong. Your exactly right 1" and 1 3/8". I'll get the circulator swapped out ASAP and take it from there. Any recommendations to address the piping without having to re-pipe the whole system??