Indirect hot water heater heats the house

john_the_tweaker

First of all, pardon my ignorance.  I don't know much about heating systems but I'm trying to learn enough to troubleshoot my current situation.  i have a peerless series 61 gas fired boiler and an amtrol boilermate indirect hot water heater.  A taco pump and honeywell aquastat sit between the two. 



My problem is that when the hot water heater calls for heat, the boiler fires and in addition to heating the hot water, also heats the radiators in the house.  The house is single zone, with a thermostat which is currently set to "off" since I don't need heat yet.



The hot water heater only has one control, a knob that goes from 0 (off) to 6.  The only temperature indication is 120 degrees, printed next to the "2" setting.  It's set to 4.



The aquastat seems to be a very simple device, not sure what model it is, but it's very thin and only has one temperature control,  which is set to 130 degrees.



Is this a matter of adjusting the settings?  Any help or indication on how to go about troubleshooting this would be appreciated.

JStar

...

Sounds like the heating pump is running, or a check valve isn't holding.



Is it possible to take pictures or make a drawing of the boiler piping?

john_the_tweaker

pictures

Pictures of the same plumbing from different angles.

billtwocase

I'd like to see

The supply pics, and where the return enters the boiler-above or below the heat circ?

john_the_tweaker

Return and supply

as connected to the heater.

john_the_tweaker

supply boiler connection

Here is the supply line as it connects to the heat circulation and connects to the boiler, and at the bottom the return line going behind the bolier to its connection on the other side.

john_the_tweaker

boiler return

Here is where the return line connects back to the boiler.  Two shots of the same thing with different exposure (sorry this is a very dark spot).

Mark Eatherton

I see a steam boiler...

Kinda like "I see dead people", but not quite... :-)



There is supposed to be "special" wiring on this system that limits the operating temperature of the boiler to 180 degrees F whenever there is a call for DHW. If not set up correctly, the boiler will produce steam, which will find radiators to give up heat.



I think you may need to bring in a truly qualified steam expert to eliminate your problems...



Also, that is the wrong type of pump for this app. It is a ferrous body (cast iron) pump which is guaranteed to rust out in short order, I normally like to see a good old Bell and Gossett BRONZE series 100 pump in that application. Ex$pen$ive? Ye$, but so is replacing that pump every 3 to 5 years... To say nothing of having a mad wife who had to take a cold shower... Not a good way to start the day :-)



ME

john_the_tweaker

I guess now I know what this is

Is this the "special wiring" you're talking about?  These 2 boxes are connected to the aquastat, the taco, the boiler tank, and the power switch.



I took the face places off for the picture.  The inside of the bottom box has a springy coil which may be the culprit?

Mark Eatherton

Pressuretrol versus aquastat

The springy thingy is a pressure control for when the berler is making steam. If you get a simultaneous call for both DHW and Steam, the boiler will go to steam production. The house thermostat should be wired through the pressuretrol. The DHW call should be wired through the aquastat AND the pressuretrol. I suspect you have a failed aquastat that is allowing the boiler to go to steam production levels on a call for DHW.



Easy enough to trouble shoot. Turn house T stat down. Call for DHW by running shower. When boiler fires, keep an eye on the steam pressure gauge. If it needle lifts off of the peg, you are making steam, and shouldn't be.



These controls are supposed to be wired in series, so if one fails (aquastat) the other one acts as a high limit to keep from sending your boiler into your neighbors back yard, assuming it (pressuretrol) is not defective. The pressuretrol should be set as low as possible. You don't need more than 2 pounds of steam EVER.



Generally speaking, on a call from the tank stat, it enables a dual pole relay. One pole energizes the circulator (120 volts), and the other pole energizes the burner (24 volts), through the aquastat to limit the boiler fluid operating temperature below the steam production level. I do believe this low voltage call is wired in series with the pressuretrol, so that if the aqua stat should fail in a closed position, the boiler pressure is still limited by the pressuretrol. The setting of your aqua stat is lower than normally seen, and indicates a possible "issue". Could be something as simple as needing to replace the limiting aquastat.



When the house T stat calls, its signal is run through the pressuretrol, which limits the operating pressure during a steam call.



Do the test and get back to us.



ME

john_the_tweaker

Test

I did the test.  The heat came on.  The pressure gauge didn't move though.  It seems to be stuck at -26.5 PSI.  I'm not sure I've ever seen the gauge move... but can't say that I've paid much attention to it.  That's not the "peg" either, that's just under -30.



Re: aquastat - thanks for the education.  I guess I didn't really understand what it does.  I thought that the purpose of it was not to limit the boiler's operating temperature, but to reduce the frequency that the boiler fires if the temperature fluctuates near your desired temperature. 

john_the_tweaker

one more thing

I also lowered the setting on the aquastat to 110 while the boiler was running and generating heat.  This got the boiler to stop.  I'm going to run like this for a couple of days and see what it does to the water temperature.  The pressuretrol doesn't seem to have anything that can be easily adjusted.

Mark Eatherton

Bad gage???

If in fact the pressure is -25 PSIG, you COULD boil water at room temperature.



It is fairly common for gages to go/be bad. Try replacing it and do the same test.



ME

john_the_tweaker

An update

Since lowering the aquastat setting, and running like that for several days now, everything seems to be working correctly - meaning:  the water heats up to the desired temperature, the boiler fires when hot water is needed, but the house heat does not come on.



I realize this does not make much sense and that I should be able to set the aquastat at a much higher setting and still cut off the boiler before steam is generated.  This whole experience has been a lot of trial-end-error to see what works and I may have finally stumbled upon the settings that work.



This thread taught me a lot though, and now I have 3 things on my list to be looked at next time my system is serviced:  The aquastat, the pressure gauge, and the hot water pump.  I appreciate the education and everyone's time responding.  If there's anything else I'm missing please let me know.