DHW temp too low during warm weather


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Old 04-17-16, 09:15 PM
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DHW temp too low during warm weather

I have a tekmar 260 with outdoor reset and whenever the outside temps rise, my DHW max temp lowers. Is this a settings issue, wiring problem or a plumbing problem? Can't get a straight answer from the co that installed it about 8 years ago. Thanks for any help or advice you can give
 
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Old 04-18-16, 12:35 AM
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Application Brochure Mar 2009 - Present
http://tekmarcontrols.com/images/_li...e/260_a_06.pdf

Installation & Operation Manual Mar 2009 - Present
http://tekmarcontrols.com/images/_li...e/260_d_06.pdf

If you have a high-mass boiler a slow response from a cold boiler is to be expected.
If terminals 3&4 on the 260 are connected to the DHW aquastat then boiler target temperature is 180F, --If you need more than that something is wrong.
Enter the installer programming mode and rundown the ADJUST settings from the quick setup guide in the I&OM [p 14, pdf] and record all. Also record the dip switch settings, then compare all settings to defaults.
 
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Old 04-18-16, 05:19 AM
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Has the system always operated like this?
 
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Old 04-18-16, 08:05 AM
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It would help to know the make and model number of what sensors/triggers/controls the DHW temp? It is the thing that connects to 260 terminals 3 and 4.
 
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Old 04-18-16, 05:59 PM
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Where everyone is going is it sounds like it is being treated like a heat zone and not DHW. When the DHW calls it should override ODR and run up to the higher temperature which is usually 170f or 180f.
 
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Old 04-18-16, 06:32 PM
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@HeatWorm- don't know about high mass.Have a WM Ultra Oil(UO-4), 146,000btu.Never been a slow response issue, just max temp. Hot in cold weather, lukewarm in warm weather.Settings are all at defaults.Dip switches are down(off), except 2nd one which is set to valve(up).
@Geochurchi- always done this. Long story why it's an issue now...marriage...
@doughess- boiler as mentioned above,sstore ultra IHWH 80gallons,tekmar 260 to taco SR504
@All- #3 has 2 wires(1to taco 24VAC,1to tekmar#1)#4 to superstore thermostat
 
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Old 04-18-16, 07:19 PM
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If the boiler has hot water (+140F) and the circulator is pumping it through the tank then the tank thermostat is suspect.

Looked at one manual on Superstor and found it of little help: http://www.htproducts.com/literature/lp-83.pdf But note on page 3 the chart and warnings about scald temps. Tank temp should always be below 120F

Without a thermometer on the tank there is no reading of tank temp. Would suggest you get a digital thermometer with small thermo couple tip that can be slipped in between the actual water tank outer surface and insulation to measure temp. I keep mine at 113F. If your is much lower I would temporarily jumper 3 & 4 while watching the temp. If you can get it up to 110F to 115F then control thermostat is the issue.
 
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Old 04-18-16, 09:49 PM
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Ok. Duplicate Application Drawing A 260-2 [page 3, pdf] ASAP!
 
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Old 04-19-16, 07:14 AM
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The Tekmar 260 display icon for DHW only shows if the circuit is active/pump "ON" that based on set up conditions and thermostat.

The question here is what is limiting the temperature. If the water temperature does not get hot with 3 & 4 temporarily shorted then check the circulator pump. Have a similar system. Last year my Taco 007 pump went bad. The impeller disintegrated and both pump ports were blocked.

To see when the tank thermostat is calling for heat you could wire a 24 Volt LED across 3 & 4. When LED is OFF there is call for heat. When LED is ON there is no call for heat.
 
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Old 04-21-16, 04:48 PM
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When the DHW demands more heat does the DHW symbol show on the Tekmar control? What is the setpoint temp when the DHW demands? Does the boiler get to the setpoint temperature? The DHW aquastat is wired to the tekmar 260 dhw terminals?
 
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Old 04-23-16, 05:48 AM
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An Ultra should not need to have an external ODR control like the Tekmar 260. When installed and wired correctly, with the Ultra's outdoor sensor and the indirect piped and wired directly to the Ultra control, the Ultra will take care of ODR and an indirect when programmed to do so.
 
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Old 04-23-16, 02:17 PM
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According to the manual there are also different ways to pipe that boiler.
 
 

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