Indirect hot water off a steam boiler - boiler wont shut off...

jim s_2

Kind of hard to tell from the diagram where and how the pipes tie into the boiler.

If the boiler runs long enough to produce steam it sounds like a wiring problem.

Michael P. Bourque

Indirect hot water off of my steam boiler - boiler wont shut off

I had a new steam boiler put in about six months ago. Since my older stream boiler had a tankless built-in, I decided to get an indirect water heater installed off the new boiler. The indirect is a super store 50 gallon.

I made a sketch of the way my system is hooked up:



The indirect has a water pump attached that is controlled by a thermostat built into the water heater. The water pump will force cooler water to flow into the boiler and on the other side of the boiler is a pipe that goes back into the water heater.

The boiler has a honeywell thermostat that keeps the water temp at least 160 degrees. The thermostat on the water heater is set to 130 degrees.

Since the boiler is kept at 160 (or above) and the water heater will turn on the pump on when the water temp gets below 130, the water in the heater coil gets cycled through the hot boiler water and thus makes hot water.

However I had a few problems with this configuration that have me worried.

- Occasionally the boiler does not shut off and the house overheats 10 degrees above normal. The house thermostat is not calling for heat, but the boiler keeps going. No hot water is being used in the house. I had the installer come out and relocate the thermostat and it still happens sometimes.

- Occasionally I run out of hot water. I don't have a big house, and only have a shower stall. My shower head might be serving too much water output, but still it surprises me.

- Energy. Is it good to have my boiler be constantly set to 160 degrees. Seems like a waste.

The wiring is as above. I DO NOT have any relays such as a TACO installed and my boiler thermostat is only hooked up to control only one side of the 160. However it is rated as a two stage.

The boiler thermostat sensor is mounted just as the heated water exits the boiler and back into the water heater. Seems to make sense but I am not sure why I am having my problems.

Looking for some advice.

Unknown

I agree

Pics would help alot .

160 degrees should not be sending steam into the system . Is the aquastat well lower than the water line all the time ? I'd check the wiring by disconnecting one wire from the thermostat , and make sure the boiler aquastat is working right . Would you happen to have a infared thermomoeter ?

There could be a few reasons the indirect is running out of hot water too fast . Are the supply and return pipes below the water line as well ? What size pipes ? What brand indirect and boiler do you have ? When the indirect's circ is running , does the return pipe get red hot ?

Could be a bad circ , broken dip tube , air in the indirect's zone , maybe the boiler aquastat is set too low . Have you been running out of hot water since the install ? Do you have plenty of hot water when the boiler is steaming ?

Michael P. Bourque

I think the diagram is pretty accurate representation of what I have. I have pics, but they are really hard to see.

The indirect in/out is very much lower than the boiler water. In fact it's very close the the ground as in my pic.

In looking at this article:

http://www.heatinghelp.com/pdfs/346.pdf

I do not have a mixing valve nor do I have a flow control valve or bypass tee. I wonder if this is what I need. Also I wonder if I need a relay switch to ensure that when heating the water while the house therm is off, will cause the boiler temp to never go high enough to produce steam.

bob young

again-----read instruction mamual...here we go again.

did the boiler & indirect come furnished with piping & wiring diagrams ? if so did you follow them ? rather than re-engineering a new installation , it is usually a good practice to review the manufacturers recommendations. they invented it so who knows more about how it will work best than them ???? and then there is your warranty & gauranty issue. improper installation VOIDS stuff like that. where did you find these plumbers ??? usually piping sizes & correct arrangement are critical to proper results.

Unknown

" I do not have a mixing valve nor do I have a flow control valve or bypass tee. I wonder if this is what I need. Also I wonder if I need a relay switch to ensure that when heating the water while the house therm is off, will cause the boiler temp to never go high enough to produce steam."

The relay in itself will not stop the boiler from producing steam . That is controlled by the aquastat in the boiler and the steam thermostat .

We really need to see pics of the system to better help . But I can guess why the indirect is not getting hot . Are both supply and return pipes the same level in the boiler ? The water might just be sailing right through without picking up any heat . Not a problem when the boiler is steaming though . I've seen it before .

allenh

More details & pix would be nice. Like the wiring.
You have a few issues.
On the boiler running you want to determine why its running. Thermostat wiring eventually goes to boiler and called T. T.
I would wait till the boiler was running on its own and then lift one wire at the thermostat. *Make sure you do not touch the wire to anything else.* Or if you know how to use a meter measure it both leads with an a.c. meter. If its zero volts that says the thermostat is calling (could be a simple anticipator adjustment). If it measures ~ 24 volts a.c. then the thermostat is satisfied and boiler should not be running for that zone. You can do the same measuring at the boiler on T.T.
On super store your drawing shows the circ pump on the cold side. I think that pump is supposed to be on the hot supply side - but check their documentation. I think that you should have a vacuum breaker in there too.
Do you have a control relay like a TACO in addition to what you supplied?

ed wallace

160 degree

you need a taco control to control burner and circulator at same time also need a check valve to keep water flow from circulating when boiler is making steam and circulator is off

Tony Massi

Hot Water

Hello, Looking at the diagram it would seem that the boiler water to the indirect is in the same part of the boiler ( supply & return ). It would work if the supply and return were at different parts of the boiler. That may be the reason you can't get enough domestic hot water. As far as the boiler over heating the house the aquastat may be bad or the well its in might have a build up of rust or gunk. You skimmed that boiler after the install, Right?

allenh

if the SS indirect has 2 sets of contacts one could be used for circ pump. And the second set for T.T. However I would add a high limit thermostat directly on the supply side to indirect and have that set up to shut down boiler over that 160 degree temp (BTW - would running this brand boiler at a low temp be o.k.?). If the taco controller has a big call for domestic hot water it will keep that boiler on for a long time, generate steam, and the house will get heat and overshoot room temp. That is why I would want another high limit specifically for domestic hot water wired between the SS controller and T.T.
And from the house that thermostat could run the boiler to its high limit. I am not a fan of a boiler sitting at 160 all the time for cost reasons.
You have a very good point about a flow check for the indirect as when calling for heat there could be some flow which could bring the indirect over temp. I suppose a mixing valve would also work.
OP said how the heat was overshooting due to boiler running. That is where I would start the troubleshooting. I would guess that is either the thermostat or anticipator setting or long calls for domestic hot water.
Without pix or wiring diagrams its hard to guess what is going on.

propmanage

Hot water

Do you have a check valve on the water feed to the tank?

propmanage

Hot water

Do you have a check valve on the water feed to the tank?

propmanage

Hot water

Do you have a check valve on the water feed to the tank?

propmanage

Do you have a check valve on the heating feed water supply?