Indirect water tank, not enough hot water, Limitless hot water? HA!

Sidekicks

All,
I have the Burnham Alpine 105 furnace with an Alliance SL 35 gal indirect water tank. Recently my kids are getting baths and the first guy gets nice hot water. The second guy takes a bath 20 minutes later and there's not enough hot water. The water is luke warm if that. I run downstairs to check out the system and I see the TPI immersion control is off. Its not calling for hot water. But when I wait a min, the light comes on the TPI, and I hear a 'click' from the TPI controller. It blinks and clicks for about a minute (thinking its calling for hot water) and it stops.

When the plumber installed my heating system, he said that the 35Gal tank was good enough for the house.

I ordered another TPI immersion controller. Do you think this is the culprit?
Thank you all for your help!

Jamie Hall

It may be the controller -- or the controller settings. Or it might be the overall system. Your boiler -- flat out -- has a capacity of 83,000 BTUh out put. That translates into about 2.3 gpm flow, if all of it's output is directed to the indirect. A tub will take all 35 gallons of hot water in the tank, and after that you are dependent on the boiler recovery -- so 20 minutes perhaps between tubs may give you warmish water, assuming there are no other draws in there.

Something to think about -- and if the controls are not set to demand all the possible heat to go to the indirect, it will be worse.

kcopp

You may want to just opt for a Honeywell 4080B control. A bit simpler.
Is there a mix valve on the indirect?
How old a water heater? Those stonelined tanks w/ the copper coils are known to scale up...

mattmia2

did it keep up before?

STEVEusaPA

Back to back baths? 20 minutes apart? 35 gal. indiect?. Coldest weather of the winter.

HVACNUT

Is the indirect wired to the boiler (not a zone panel) so it knows to override any economy settings?

Sidekicks

kcopp said:

You may want to just opt for a Honeywell 4080B control. A bit simpler.
Is there a mix valve on the indirect?
How old a water heater? Those stonelined tanks w/ the copper coils are known to scale up...

Would this be easy to hook up? I have 4 wires on the TPI controller now. If its self explantory, I'll order it.

No mixing valve that I can see. I can take pics for you guys if you want.

The heater is about 9 years old

Sidekicks

mattmia2 said:

did it keep up before?

See here's the thing. When I was single, I didn't know. When it was me and my wife, didn't know.

Now with 2 kids and 2 adults, we know now!

pecmsg

What temperature are you running the tank at?

Sidekicks

HVACNUT said:

Is the indirect wired to the boiler (not a zone panel) so it knows to override any economy settings?

Yes I followed the wire and it goes from the TPI controller to the boiler. I checked a few minutes ago.

mattmia2

Once you figure out that the control is indeed calling when the part of the tank with the sensor sees a sufficient temp drop, you might need to run the tank at a higher temp and use a mixing valve to keep the water at a safe temp to get enough hot water out of the system.

Zman

I would start by verifying a few things. Watch the boiler during the cycle you are having issues with. Does the boiler come up to full fire immediately after the tank temp drops and continue at 100%? Does the heat turn off (DHW priority) so you have all of the boilers energy going to make hot water?
If this checks out, you may need to either run your tank hotter and add a mixing valve so you don't boil the kids or get a larger indirect.
Filling the tub more slowly may also help.

mattmia2

Stagnation will tend to mean it won't see a temp drop at the control until you have been drawing water for a couple minutes.

Sidekicks

I'm going to change out the TPI Controller now. I bought one so might as well change it out right?

Zman

Sidekicks said:

I'm going to change out the TPI Controller now. I bought one so might as well change it out right?

Some thermal grease in the sensor well is a good idea. You want to make sure the sensor is reacting as quickly as possible. On some models the depth of insertion is critical.

Sidekicks

Okay so the aquastat did fix a few issues. It doesn't click when it's calling for hot water. 

So I asked my wife how was it when bathing the kids. Once in a while she tells me that's there wasnt enough hot water. But not all the time. She can bathe one kid and then we will have to wait 15 min to bathe the other kid. 

Still stumped. I can show you pics if needed. Let me know 

Also I have another issue. In the back of the Alpine, there are two pipes, one for vent and the other for exhaust. Well it seems that BOTH pipe is were leaking water. I placed a two gallon bucket under the drops and it took about three weeks to fill it up 3/4 of the way. What could this be? The Alpine is still condensing as I hear the pump filling and pushing the water to the slop sink. 

I can get a pic of that as well where it's leaking.

Sidekicks

flat_twin

Sounds like the new aquastat got you most of the way there. What temp is the new aquastat set? As suggested already, raising the aquastat setting and adding an anti scald mixing valve essentially increases the size of your water heater. Another good reason to raise the tank temperature is to kill legionella (140 degrees).

Sidekicks

flat_twin said:

Sounds like the new aquastat got you most of the way there. What temp is the new aquastat set? As suggested already, raising the aquastat setting and adding an anti scald mixing valve essentially increases the size of your water heater. Another good reason to raise the tank temperature is to kill legionella (140 degrees).

I think I pushed it to 150-160. Not too sure. Have to take care of other emergencies in the house

kcopp

Sidekicks said:

The flue sensor looks like it has broken off the stainless termination. You are leaking flue gas each time the boiler runs. This needs to be fixed.

JohnNY

First of all, who told you using an indirect water heater meant having "limitless hot water"?
That's not a thing.
Second, there are clearly problems with your hardware/settings/installation, etc, so you should consider changing the title of your post for people who come here looking for guidance and information about indirect water heaters.
Third, all indirects should be fitted with a mixing valve. It's not imperative but for safety reasons it's good practice when the heat source is a space heating boiler that regularly makes 180° water. Where I live in NYC, most inspections require it.