Weak Heat - Buderus 215 w/Logimatic 2107

zooba72

Hello everyone,

I need some assistance with my heating system if someone has some time.

I own a Buderus G215/4 boiler with Logamatic R2107 for my residential home with three heating zones: 1-Living Area 2-Basement 3-DHW

I have an outdoor temperature sensor which appears to be functioning properly, but I do not have any Bfu Remote Control devices in my heating zones; I simply have standard Honeywell thermostats and a Taco Switching Relay to control temperature in the two zones. We do not use any heating programs on the Logamatic. Approximately a week ago, I noticed that when the thermostat made a call for heat, the heat coming out of the convectors was very weak. I have a split mono-flow system and I did try to bleed air out of the system but it did not improve the situation. I noticed the boiler temp was hovering around the 207-210 degrees – When I switched the Logimaqtic into manual mode I had strong heat. A couple of days later I noticed a “Boiler Sensor Error” on the Logimatic. I replaced the FK sensor that runs from the Logimatic to the sensor well at the back of the G215. I no longer have the boiler sensor error and I’m getting what I believe is an accurate boiler temp reading somewhere around 120 degrees. I turned the aquastat dial back to Auto/190, switched the Logimatic back on automatic, and turned up my thermostat but I have the same issue I had initially – the water circulating is not hot and the heat coming out of the convectors is very weak.

Anyone have any thoughts ?

HVACNUT

Ah but are the zones able to satisfy the thermostat? With ODR, that's all you want. The lowest possible temperature, to match the heat loss of the envelope.

If the zones aren't keeping up with the demand, you might need to adjust the reset curve.

Is the outdoor sensor on the north side, in the shade?

It's a 10K resistor. The table is on page 57 of the manual.

zooba72

I appreciate the response - You're spot on with the location of my outdoor sensor, it's on the north side of the house and it's shaded. Unfortunately I'm a bit lost with what to do next - I'm looking at the FA temp curve on page 57 but it's still not clear what my issue is. Can you elaborate ? Thank you !

HVACNUT

You need an ohmmeter to check the resistance of the sensor. Does the OA temp reading on the 2107 closely match actual outdoor temp?

If you have the thermostats set to 70°, is it 70° in the space?

zooba72

The OA Temp is right on target - 43. It was reading 39 this morning which was also accurate. The boiler temp is reading 106 and the DHW is 127.

HVACNUT

Are
The
Zones
Keeping
Up
With
The
Thermostats?

BDR529

You need 180 degrees to get the convectors to work properly. A 2107 or any outside reset control will make it difficult to get the "chill" out of the house.

zooba72

Thanks again for the responses. When running the Logimatic on automatic mode, we are no longer keeping up with the thermostats. When I switch to manual mode, Yes, the convectors get very hot and easily match the thermostat demand. I'm really not sure what might have changed. This has been working flawlessly on automatic mode for eight years. I thought for certain that the "boiler sensor error" was my issue and was surprised to find myself having the same issue.

HVACNUT

You're gonna have to access the service level and make sure everything didn't default to factory settings.
Power surge?
Grab the book and a paper clip for the "Key" and check or adjust.
You need to know the Design Day for your area to set outdoor reset. In the book they refer to it as outdoor setback.
Start at the beginning (American) and go through all settings for the heat circuit(s).

GW

106- not good

Get into the installer menu (torn page button and tiny pencil tip button together) and scroll, what’s your ref temp? Should be 170 or so

What’s the offset?

Then scroll to see the curve, there’s 3 numbers to look at. I can’t remember super well unless I’m in front of the control, you may need to hold the torn page button to see all three “curve” numbers.

It is odd- you said you had a boiler sensor error?

Big Ed_4

I am assuming the clock is correctly set .. The moon and the sun is not am pm out ?? When you replaced the sensor did you noticed water in the well ?

zooba72

Thanks Everyone I'm going to get answers to the temp questions above and respond back tomorrow. The unit did not reset to factory default - but I was considering doing this myself. I understand it goes back to German when you do this.

One piece of information that I should add - This entire situation started after my heat came on during the day and I wanted to start my wood stove, so I somewhat aggressively turned down the thermostat - meaning I pushed it back quickly. Ever since that incident, it hasn't worked properly. I don't see how it's relevant but figure it's worth a mention.

Clock is off by an hour - I will set that up again tomorrow. I think it's daylight savings that through that off.

HVACNUT

If all is fine and dandy when you switch to manual, then it's not thermostat, or water related.

There's no error codes.

Go through the settings on the 2107.

zooba72

I agree the issue is most likely a configuration on 2107 - but I did not change anything.

Current temperature settings appear to be the default:
- Reference Temp = 167
- Offset = 0

Big Ed_4

The BF room sensor is not really a thermostat as normally used . It adjusts the heat curve in the processor and a remote to override the setback program ... You may what to check out to see if its working properly ..

HVACNUT

> @zooba72 said:
> I agree the issue is most likely a configuration on 2107 - but I did not change anything.
>
>
You know how the Germans are. They have vays uf making you brain like dos strudel.
We call them Gremlins.