I have a GV3 MCW boiler connected to a 5 zone baseboard heat system with Taco zone controllers. Domestic hot water is supplied by an amtrol indirect water heater with a Taco 007-f5 on the return side to the boiler.

A few weeks ago we had a power surge that knocked out many appliances in the neighborhood, including the Smart thermostat control on the Amtrol indirect water heater. I replaced the smartcontrol and set it to 120F.

To cut a long story short, the domestic hot water is too hot- at 155F. I have noticed that there appears to be hot water circulating even when the Taco circulator pump is not activated. (The circulator pump does switch on for 15-20 after someone takes a bath).

Any suggestions would be greatly appreciated.

 

Harry, it's possible that there is a 'stuck' flow-check valve on your system that is causing heated water to be applied to the amtrol when space heating is being called for.

Can you tell if there are any check valves in the lines to/from the Amtrol ?

 

Many thanks for your quick response.

No. I don't see any check valves on either side of Amtrol to/from boiler.

(There is a Nibco ball valve that I thought might contain a flow check, but I don't see such a combination on the Nibco website.)

 

It's possible that your circulator has a built-in check valve, and this would be indicated on the circulator by the suffix -IFC (internal flow check) on the model number. Or if not in the model number, at least _someplace_ on the circ itself.

Is this a problem that only showed up with the power surge ? or has it been doing this all along ?

 

Well I've looked and looked but can't see IFC written anywhere on the Taco circulator in the Amtrol to/from boiler circuit. Also I cannot see a flow check anywhere else on this circuit.

Also, not sure if this helps, but I've tried lowering all the 5 zone thermostats and then raising each in turn. Turning on any individual zone results in water to circulate in the Amtrol circuit.

Yes, the excessively hot water is a new problem and I think coincides with the colder weather and use of the heating. The power surge happened in the fall, before we started to use the heating.

Incidentally, not sure if this helps, but the water pressure in the system is ca. 20psi, and the temp ranges 140-180F.

 

My gut feeling is that even though the symptoms seem to have appeared around the same time as the power surge, that it's coincidence.

I'm assuming that you've lived in this home for a few years ? or is this the first winter with the system ? If so, I suppose it's possible that this situation has existed all along... it wouldn't show up during the summer if the house wasn't calling for heat because the only time the boiler would fire would be when the Amtrol was calling.

Harry, can you take some pictures and post them on www.photobucket.com (free) and provide a link here so that we can have a look ? We might see something that you might have missed ?

It does sound like you need a flow-check valve in there. It could be done fairly easily by swapping out the circulator with one that has one internally, that way, no piping changes.

I wonder... does the 007 circulator look newer than the rest of the system ? It's possible that at one time that circ HAD a flow-check, and if it were replaced, they may have put the wrong one in as a replacement... just thinking out loud here...

 

NJ Trooper - thank you- I really appreciate you comments on this.
It's our second winter here- don't recall the water being so hot. Yes, I agree it could be a coincidence.
Sorry it took a while: here they are the photos:

http://i264.photobucket.com/albums/i...8/DSCF0999.jpg
http://i264.photobucket.com/albums/i...8/DSCF0996.jpg
http://i264.photobucket.com/albums/i...8/DSCF0995.jpg
http://i264.photobucket.com/albums/i...8/DSCF0994.jpg
http://i264.photobucket.com/albums/i...8/DSCF0988.jpg

A couple of thoughts; is it possible that the circulator 'fins' are broken- allowing free flow?
Also, is it possible that one of the GV TACOs is defective- causing a pressure imbalance?

Yes, I agree, I could change the pump to one with an IFC- is it absolutely identical in size/fittings?

 

Harry, I don't think changing out the circ will help with the system piped as is... the circ for the amtrol being on the return, will have the internal check valve pulled open by the system circ installed in the boiler. If you have the Amtrol install brochure, they caution against this... I'm not quite sure what the solution will be yet, but I can tell you that the problem has more than likely been there all along, and is not related to the replacement of the control after the power surge.

The installer of that system did also not follow Amtrols recommendation to install a "heat trap" in the hot water outlet, whereby the outlet pipe drops down in a "U" before heading back out to the house. This prevents gravity flow of the hot water in the piping. This of course has nothing to do with your existing problem, just something I noticed while viewing your pics.

I don't see any expansion tanks... there must be one for the boiler, but out of the pictures ? Amtrol also recommends one on the domestic water side too.

It also appears that there is some problem with the condensate drain on the boiler... evidence the spill underneath the tee on the flue pipe. Is that the drain line in the pics that goes somewhere into the wall at floor level ?

No, broken 'fins' on the pump are not likely... those pumps are 'centrifugal' and don't actually have 'fins' to speak of, but all circulators will happily pass water through them, there is nothing there to stop it from flowing when the circ is not running.

Not likely either is a defective zone valve causing the problem. It's definitely a piping issue, but how to correct it would still be the question.

 

As much as I don't want to say this, I think the only solution to your problem is going to be ditching the circulator on the Amtrol circuit and installing a zone valve in it's place.

In order to prevent flow in the Amtrol when a zone was calling for heat, you would have to pipe the return for the Amtrol into the boiler AFTER the internal boiler circ... not possible.

 

I don't see the problem with DHW circulator's
location. Regardless if it is on the supply or
return, the flow direction will always be the
same through the DHW circulator. An internal IFC valve will be "pushed closed" by the
return pressure flow on the heating loop
side regardless of which side of the DHW
tank it is located on.

The DHW tank should have a circulator with
an IFC, and the other port should have a
gravity flow check to stop the possibility
of single pipe gravity feeding...

A pressure tank on the DHW is only really
needed if the house has a pressure reducing
valve from the street, or a check valve in
line... It should have a vacuum breaker to
protect the plastic lining from suction damage
however.

Pete

 

True that it wouldn't matter whether the Amtrol's circ was on the supply or return, the system circ in the boiler would still be sucking the check valve open. The two circ's appear in series the way it's currently set up.

In order for this to not happen, the return for the amtrol would have to go to the OTHER side of the INTERNAL CIRC INSIDE THE BOILER JACKET, and then what you said would be true, the system circ would push the check valve closed. This GV boiler has the circ on the return, along with a pumped boiler bypass circ, both inside the unit, no way to gain access to the return directly into the boiler because of this.

 

I don't think all the pieces of this puzzle are here. Can you post pic's of the rest of the near boiler piping. I think it may help to look at the supply piping.

 

Here are some additional photos.


http://i264.photobucket.com/albums/i...8/DSCF1022.jpg
http://i264.photobucket.com/albums/i...8/DSCF1021.jpg
http://i264.photobucket.com/albums/i...8/DSCF1012.jpg
http://i264.photobucket.com/albums/i...8/DSCF1007.jpg
http://i264.photobucket.com/albums/i...8/DSCF1004.jpg


I've also included a picture of the condensate drain.

The amtrol model I have is WH-7P. Also, I should mention that water is supplied from a well. Would it help to flush the system?

 

Harry, you removed the other pictures ?

Here's what I see (saw) in the pics:

The Amtrol supply is teeing out of the vertical section of the supply pipe, across the wall into the Amtrol.

The return from the Amtrol comes out, over and down into the purge station, then into the circ, then into the return header.

Return header goes straight into the boiler, where the system pump is located.

What I see is that the amtrol circ and the system circ are in series. There's no way to install a check valve.

If you look at Amtrol's I&O, they specifically warn against this, citing the exact symptoms, (and error code ER2) that Harry is experiencing.

unrelated to the overheating indirect, I'm a little concerned about the vent piping ... does that look OK to you rbeck ?

 

let me try again..

 

http://i264.photobucket.com/albums/i...8/DSCF1007.jpg

 

My apologies rbeck- when you wrote 'see pictures around boiler piping'- do you mean pipes around the Amtrol or around the GV3 boiler- or do you now have sufficent?

 

Am I missing it or are we missing a circulator for the zone valves?

 

picture of circulators in GV3 boiler..

http://i264.photobucket.com/albums/i...8/DSCF0994.jpg

 

The W-M GV series have internal circs... one for the system, and the other is a pumped boiler bypass.

 

What does W/M show for suggested indirect piping
in the install manual?

Pete

 

Good question! The short answer is:

They DON'T ! Nada, Zip, Zilch, NoGotz ...