Vaughn S50TPP - issues

tyracz

Good morning Gods of Heating! I am coming here to hopefully get some info that will help me to figure out my current situation.

I do have Buderus Logano G115 oil fired boiler. Aquastat is set to 180F and water is fed to 2x XPB Taco mixing blocks - they are supplying 120-125F to the radiant heat in my entire house.

Also on the supply from the boiler, I do have separate line going to Vaughn S50TPP - (it was manufactured in May 2007) indirect water heater. There is Honeywell aquastat sitting in the water heater well set to 120F.

My issues is :

Circulator on water heater line almost never shuts off. It will run all the time even tho when i measure temp in the faucets in the entire house, water is 130F.

My first thinking was "you need new aquastat", so I picked one up in Lowes - (now seems like Honeywell is called Resideo now?)

Box was taped with clear tape so I was a little skeptical but aquastat itself looked brand new (only front cover name Rasideo looks a little roughed up...). I installed new aquastat and I fired the system back on thinking it will help...well....24 hours later my circulator is still working and faucet temp is 130F. This morning I changed the setting from 120F to 100F and circulator turned off BUT as soon as I went to 110F it turned back on. My differential is 5F - aquastat I purchased was Model #L4006A1967, same as old one.

Supply from boiler is 160F and return to boiler is 150F at all times. As soon as boiler starts to heat up water in main line, supply to water heater goes up and return as well.

I tried to drain the water from entire water heater thinking I may have some crud on the bottom and try to flush it out - after heater was empty, I looked thru drain when i removed it, hardly anything on the bottom. I removed immersion well where aquastat sits to check the heating coil inside, just a film on the coil, I didn't see any major buildup.

Immersion well is copper and from what I can see it was in ok condition. I placed back immersion well and drain in the heater and filled it slowly back up making sure I purge all the air from it leaving 2 faucets in the 1st and 2nd FL open.

I turned my taco 005-F5 circulator back on and let it heat up again. Boiler turned on 3 times to heat up water in main line and I am back to the same point where circulator works all the time....

I pulled out aquastat from the immersion well and noticed that sensing bulb is no warm at all, so I took it upstairs to see if it is working. I started hot water in the sink and i set dial to 200F. After 1 min of heating up bulb with water, I started dialing down and at 130F, aquastat clicked. I measured resistance across 2 screws that would be passing 24V to my honeywell RA832A that controls my circulator and it was 0 ohms. As soon as I increased dial above 130F, aquastat clicked and I started reading resistance.

At this time I am lost, I think I did all I could to try to figure out.....so I came here to ask Gods of heating for help....!!

I am ruling leaking coil in water heater since I do not have any discharges from PRV on my boiler and my main system pressure stays right around 20 PSI all the time. I will be replacing cartridge in my 005-F5 circulator since it is making humming noise - YES i confirmed it is working by pulling it out and starting it - it spins like a devil.

Jamie Hall

The circulator is running, OK... is the burner on the boiler running? That's not clear.

kcopp

What Is your water quality like? Do you have enough hot water to take a couple showers back to back? That water heater coil has been prone to scaling up. If that is the case your heat transfer will be poor and recovery will be prolonged.
You can ul the coil & clean it. However getting the seal to be 100% after that may be an issue.

tyracz

Jamie Hall said:

The circulator is running, OK... is the burner on the boiler running? That's not clear.

Burner on boiler is running - it is controller by aquastat on the boiler and it maintains right around 180F, it kicks in when water drops to 165F.

kcopp said:

What Is your water quality like? Do you have enough hot water to take a couple showers back to back? That water heater coil has been prone to scaling up. If that is the case your heat transfer will be poor and recovery will be prolonged.
You can ul the coil & clean it. However getting the seal to be 100% after that may be an issue.

Yesterday I had 20 min shower, my wife had 30 min shower and 2 small kids had showers. There was hot water at all times, never stopped.

I do have whole house water filter that I replace each time I see it is needed - its a see thru.

My well has a lot of iron so I also do have water softener that takes care of that - I am selling house now and all the water test after water softener came back in range.

New coil with all the gaskets, bolts etc. for my water heater is 3/4 of the price of new unit.

Jon_blaney

Have you tried any tests on the control board? Reset the board, or wire the tank to a different zone?

tyracz

Jon_blaney said:

Have you tried any tests on the control board? Reset the board, or wire the tank to a different zone?

My radiant floor heat is all supplied and controlled by 2x Taco X Blocks - they do all the calculation and starting pumps.

The only separate control I do have in the system is my honeywell RA832A that starts burner+main circulator and starts circulator on my indirect tank. But that's all coming from that aquastat that doesn't read right temp. in the immersible tank well.

If i remove white wire from my aquastat (it has red-24v and while as neutral), it will stop circulator. So my thinking is my RA832A works properly.

EBEBRATT-Ed

@tyracz

Make sure the aquastat bulb is pushed firmly into the well (all the way in) and that yo use heat conductive compound on the bulb.

Otherwise it may be a heat transfer issue as @kcopp mentioned.

Did this problem start suddenly or has this always been an issue?

tyracz

EBEBRATT-Ed said:

@tyracz

Make sure the aquastat bulb is pushed firmly into the well (all the way in) and that yo use heat conductive compound on the bulb.

Otherwise it may be a heat transfer issue as @kcopp mentioned.

Did this problem start suddenly or has this always been an issue?

I just noticed it but my wife says she heard pump running all the time already year ago....LOL

When i pulled immersion well from the tank, I placed aquastat bulb into it and confirmed that it slides all the way down, my bulb on aquastat goes all the way down to the end and stops, so i know its a right well and right lenght bulb.

It may be transfer issue which sucks but it is not going to be my problem, Dec 6th i will be selling house....

tyracz

Do you guys know if there is something i can use to flush the inside of the tank and remove any rust from it to improve heat transfer?

Maybe some food grade rust remover... ?

kcopp

Even if the water in in the "range" it may still have issues sticking to a hot surface. I have seen this water heater scale up on City water more than one time.
Other than pulling the coil "fixes" are limited.
The only other option would be to drain the tank. Turn on the zone to the indirect water heater. When it gets to the hottest temperature then spray cold water on the coil w a wand through the aquastat port. Then flush out through the drain. May work...may not.
What is the change in temperature of the piping on that zone between the supply and the return? if its only a few degrees then the coil is caked w/ scale.
If you are selling it may be best to reveal the issues to the new owners now and off to give them some money towards a repair.

tyracz

kcopp said:

A simple sediment filter as you describe it not going to help w/ any hardness or scaling issues. That type of stuff is in solution and will only come out if there is a softener type filter system.
The only other option would be to drain the tank. Turn on the zone to the indirect water heater. When it gets to the hottest temperature then spray cold water on the coil w a wand through the aquastat port. Then flush out through the drain. May work...may not.
What is the change in temperature of the piping on that zone between the supply and the return? if its only a few degrees then the coil is caked w/ scale.

If i may ask, will spraying with cold water loosen the scale?

Difference is maybe 20F. At some point supply from boiler to the tank and return to the boiler are the same temperature to the touch. Both are super hot which means there is poor heat transfer.

HVACNUT

When you removed the white wire, did you do it at the RA832A or at the L4006A?
If you remove it at the L4006A and the circulator still runs, theres a short in the wiring.
The L4006A goes to TT on the RA832A, and XX on the RA832A goes to?
What aquastat is on the boiler?

tyracz

HVACNUT said:

When you removed the white wire, did you do it at the RA832A or at the L4006A?
If you remove it at the L4006A and the circulator still runs, theres a short in the wiring.
The L4006A goes to TT on the RA832A, and XX on the RA832A goes to?
What aquastat is on the boiler?

I remove it at L4006A and circulator stops right away.

If i am correct XX goes to Aquastat on the boiler - i can confirm once i get home.

Its the standard boiler aquastat that controls circulator on main boiler line and burner. I will get you info when i get home.

Zman

14 years is a pretty typical life expectancy for an indirect with that type of coil. If it were mine, I would not put a dime into it.
Do keep in mind that that tank is cement-lined and will take some effort to remove.

kcopp

tyracz said:

kcopp said:

A simple sediment filter as you describe it not going to help w/ any hardness or scaling issues. That type of stuff is in solution and will only come out if there is a softener type filter system.
The only other option would be to drain the tank. Turn on the zone to the indirect water heater. When it gets to the hottest temperature then spray cold water on the coil w a wand through the aquastat port. Then flush out through the drain. May work...may not.
What is the change in temperature of the piping on that zone between the supply and the return? if its only a few degrees then the coil is caked w/ scale.

If i may ask, will spraying with cold water loosen the scale?

Difference is maybe 20F. At some point supply from boiler to the tank and return to the boiler are the same temperature to the touch. Both are super hot which means there is poor heat transfer.

The temperature difference will shock the scale loose. That is the theory...

hot_rod

What @kcopp said, I've seen those finned copper coils scale up in a years time. I suspect yours is way past due for a descaling, or replacement. the hot boiler SWT really accelerates the scaling.

kcopp

I actually ran across one of these today. It was a 70 gallon version. Replaced because it was leaking at the aquastat well tapping. House was being sold and the new owners wanted a replacement. Tank was from 2003. I pulled the coil just to see what condition it was in...

tyracz

kcopp said:

I actually ran across one of these today. It was a 70 gallon version. Replaced because it was leaking at the aquastat well tapping. House was being sold and the new owners wanted a replacement. Tank was from 2003. I pulled the coil just to see what condition it was in...

what was the condition ?:)

kcopp

Just added the pix...

Jamie Hall

For reference a few posts back. The white wire is NOT a neutral. It is a switched (by the aquastat or thermostat) 24 volt hot.