Buderus GB System poor heat

jess askey

Hi all... Im out in Colorado and am the second owner of this system. While the original owner seems to have installed a mighty fine system with a top notch designer back in 2007... alas, there no longer seems to be anyone in the local area that knows anything about this system or how to to troubleshoot it. I have a pretty good handle on it, but now Im stumped with something new.

Some reference info... GB-142 boiler. 4 zones on primary loop, and 2 zones in secondary loop. I have DHW set to 130 (my wife likes it hot)... and Radiant Heat set to 150 at the boiler control. I took this up to help keep my house warm as it is struggling, I normally have this around 130. Im not entirely sure what the radiant loop should be running.

At the boiler output, Im getting a nice 150f (pic below). I put magnetic thermometers everywhere so I can monitor what is going on with flow and temperature. BUT, issue is that as I go just 3 feet away into the primary and secondary loop pumps, 125f max. Like my flow is super low or something... I have a little magnet tool for the Grundfos pumps and they are all spinning appropriately (primary and secondary only on call) and the main output pump anytime primary OR secondary are on.

Im sort of at a loss on where to go from here... any ideas?

Thank you oh wise ones!

Im happy to answer any specific questions or do any work. I *have* had a tech come out and do the various combustion tests etc, but the piping overwhelms everyone that has come into 'assist'.. I end up teaching them more than they teach me. :-)

jess askey

Some other followup info that might be helpful.... Primary Loop is 4 zones of radiant heat under tile.. Only two zones are actuated regularly, the main house and the garage (I keep the garage at 45f in the winter). The secondary loops is 2 zones which are for the basement and these are baseboard fins, only one zone is really ever active here (my daughters room). It is -12f outside (without windchill) right now, so I may just be hitting the BTU limit of this system? But even when it is only 32f outside, it still seems 'sluggish' in heating response.

Jamie Hall

The fin tube should respond quickly enough -- does it? However. the radiant floors will respond very slowly -- hours --even if they are working as they should. The best bet on the radiant floors is to have them running all the time, with the water temperature for them (is there a mixing valve?) set to provide enough heat.

jess askey

thanks Jaime... Yeah, I have been doing some reading and it seems like my radiant floor loop should be at 125f max... you are correct, my mixing valve (only exists on the primary loop) drops things down to about 120f... im really confused why my secondary loop (basement baseboard fins) will only get up to 125 degrees tho... seems like since the temp leaving the boiler is 150 that it should go higher with no mixing valve? Either way, I will change my thermostat setting upstairs to be a little more 'proactive' in warming which should help. Should I reduce my boiler main output temp to right about 130f instead of 150f where I have it now? I was never really sure about what that temp should be and/or why.

jess askey

I have 3 total pumps and they were all set to 'medium' II speed originally... the main boiler pump, and then the primary (4 zone radiant) and secondary (2 zone baseboard fin) loops.... seemed like when the secondary loop was running (no mixing valve), that my primary (has mixing valve) would run cooler.. I put the Primary loop pump on 'high' III and left the secondary at 'medium' II and then I switched the main boiler pump to 'high' III as well. My idea was that I was trying to lower the flow on the secondary loop a bit... was/am I doing something that makes sense or should I be putting them all back to 'medium' II speed? How long should I expect these Grundfos pumps to run before 'failing'? should I keep spares in my spare pile at this age (17 years old)? They are 'rattling' a bit nowadays. I expect that main pump runs pretty frequently being I have DHW and Radiant Heat.

Jamie Hall

Would it be possible for you to draw a diagram of your system, showing where the pipes all go and any valves (including the mixing valve) and the pumps? If you could, and post it, we can probably figure out what was originally intended -- and what has happened since, and how to get back to where it should be.

neilc

pictures of the boiler and circs, all shown in one distant shot,
make that 2 or 3 distant shots from different angles