High pressure in '08 Viessmann

driftintime

Hi all, first post here. I have a 2008 Viessmann Vitodens 200 WB2 6-24 boiler, propane fueled, with an SuperStor indirect-fired water heater. Pressure always rises in the boiler causing the pressure relief valve to do its job. Contractor is confident it must be caused by a pinhole leak in water heater; he's tested the pressure regulator valve and expansion tank, no issues there. I'm thinking I'll just replace the water heater with a Viessmann Vitcocell 300. He's also quoted me to replace the boiler, but right now the only other issue is high CO in the vent. I'm hoping a cleaning will resolve that. Do folks here think I should go ahead and replace the boiler while I'm at it? How many more years can I expect out of it? Eventually I may consider moving away from propane, though I have no access to natural gas and retrofitting the house for heat pumps may be difficult with baseboard heating today and no central A/C or air ducts. Thanks for any thoughts/advice

Derheatmeister

The Viessmann WB2A 6 24 is a good boiler..
For a long time we had the highest "A series " install in the world at 11.200 feet on propane..
The HX is bomb proof ,The Matrix burner is great.
One of the issues with the "A" modle is the LGM29.
If this is the original LGM 29 it could go out soon..
Voltage spikes and the "Hot Box" enclosure design for the Electronics kill the LGM 29..
Lately I have been replacing some of the "A "series boilers since the LGM replacement is Pricey
Can you post some pictures of the Install.
High CO could be a Crossover in the Concentric venting system or a Maladjusted boiler..

Jamie Hall

The high CO in the exhaust should have been corrected last time your technician cleaned and adjusted the burner -- that's not something which someone would measure and then walk away from. Not happy with that.

However, that is not a cause for replacing the boiler. Nor, for that matter, is the high pressure in the boiler -- though you may want to be sure the expansion tank hasn't been damaged, and should replace the pressure relief valve if it's been operating.

If you tech. -- who left you with high CO -- is sure it's not an expansion tank problem -- which it could be, but would be easily determined and fixed -- or a pressure regulating valve problem -- even more easily determined and only slightly harder to fix -- then the only other source is that indirect, and they do leak sometimes, and it doesn't take much of a leak. It's easy to check. Turn the domestic water off to that tank and open a hot water faucet somewhere and watch the pressure in the heating circuit. If it now holds constant, or even drops some, you have a leak in the tank.

Why bother to replace the boiler? If the tank is leaking, that's not the fault of the boiler. Replace the tank. The high CO isn't the fault of the boiler either, unless it's really messed up.

driftintime

Thanks @Derheatmeister. Here's a photo of the system, let me know if more detail would be helpful. Bucket on left due to the pressure relief. I'm a new home owner and have heard from two contractors that vent pipe setup and expansion tank location are not ideal. If boiler replacement now (meaning essentially the whole system since I'm planning to replace water heater) seems wise/necessary I'd do it, otherwise would like to wait longer on boiler.

driftintime

Thanks @Jamie Hall. I'm a new home owner, not sure how long it's been since last proper cleaning/maintenance or who did it. Will look to replace pressure relief valve once all done since it has been operating

Derheatmeister

By the looks of the end of the relief piping (Corroded Pipe) this could have been an Issue for a while.
Replacing system fluid on a regularly is not ideal for any of your system components incl. the Heat exchanger.

Are you on City water or Well water ?

You originally mentioned that the contractor checked the expansion tank and the fill valve and found that they are functioning and adjusted correctly..So hopefully they can be ruled out as a issue !

As Jamie mentioned you could just turn off the domestic water to the house,reduce the pressure and note if the pressure to the boiler drops..You will however create a small crossover from your heating system to your domestic...probably not a problem !
Or
If you have two isolating valves between the Boiler and the Waterheater you could
1. Remove the power to the heating system.
2. Isolate the boiler from the Waterheater via both valves.
3. Note if the pressure to the heating system stays steady...
4. If the pressure stays steady you can open both of the Isolation valves to the waterheater and note if the pressure to the boiler increases and the relief valve (Corroded Pipe) starts to leak.
5. If the relief valve starts to leak..the waterheaters coil is shot.

BTW : The Low loss header (Black iron Header in the R. side courner) is ideally installed in a vertical position and the relay (Taco 501) coming off of the pump module is questionable ..
IMO you should call Viessmann and ask them if they have anybody in your area that they recommend..
Once you found a contractor you should have them check the overall health of the System including the Concentric venting of which some of the o-rings may not be available anymore..Only then can you make a educated decision on if it is time to replace the boiler..

Paul Pollets

This boiler requires careful cleaning between the heat exchanger spaces. A special tool is required and if it's not done thoroughly, problems will develop. I've replaced several LGM29 boards, as well. Never seen a LLH installed horizontally. All piping diagrams show a vertical installation.