Buying a used Buderus G115/5

[wombosi]

Good day all.
I'm in Massachusetts and thinking about buying a used Buderus G115/5 with Riello burner and Logomatic control. It would save me about 75% of the retail cost. The seller says it's about 7-8 years old but was used in a seasonal residence. Pictures look very clean and still shiny.
My questions are:
I've run a few heat load calculators online and seem to be around 100K. I have a three story Victorian home a little over 2,000 square feet. But new windows and foam insulation throughout. However, I plan to add a radiant loop out to my shop next spring which would take the BTUs needed right around what this boiler puts out.

Is it critical to get a pro out to run a heat loss/load? When I priced out the new boiler over the phone with a local dealer, he spent all of 5 seconds asking for square footage, then told me to go with the 115/4 just to be safe, but I didn't mention the shop to him.

I don't want to use in indirect tank, prefer electric and shut the boiler off in the summer months.

Is it risky to buy used? What should I be looking for specifically?

Thanks!

 

[maple1]

My only input would likely be its always risky to buy used anything.

My father has a Buderus, think it is maybe 15 years old by now? Maybe? No issues in that time and it's used all year for DHW with the indirect. Scouring it all over for signs of corrosion would be about the most you could do I think. In the burn chamber too. That's assuming no leaks and that it will hold pressure fine.

Not sure about your heat loss. Sounds high. We have a 2 story 2700 sq ft on top of 1500 of unfinished basement. Typical 25 year old stick frame construction. I think our average is around the 25,000-30,000 btu/hr range.

 

[Bad LP]

Sounds too small to me.

 

[peakbagger]

IMO A Buderus is a cast iron boiler, unless it was major abused its got a lot of good years left. The Riello burner is also a fairly well known unit and parts are available.

As for heat load calculations you are running into rules of thumb. In theory on the coldest day of the year the boiler should have just enough capacity to keep the house at design temp while supplying a full hot water load (if the boiler supplies hot water. In that case of the coldest day, my guess is you would accept turning the thermostat down in the shop to free up heat for the rest of the house. The reality is a boiler is set up to have extra capacity to deal with things like cranking up the thermostats at the worst time or dealing with sudden heating demand like leaving a door open in very cold weather. Burner nozzles can be downsized a bit if you go too big but once you hit the boiler surface area you really can not get more heat. (Note buried in the calculations is fouling factor. I think Buderus boilers are three pass units and they need to be cleaned annually as they can partially plug up and lose capacity. I have heard some speculation is that the switch to low sulfur fuel oil keeps the boilers cleaner.

So if you go small you are trading off some flexibility with the system, the house takes longer to come up to temp in situations like when you come back from vacation with the thermostats turned down. Go too big and the boiler can short cycle but you can have the tech put in lower rated nozzle (with in reason)

IMO Mass is going to be putting in major incentives to upgrade away from fossil fueled boilers and the cost of heating oil is going to be going up in the long run. Odds are the boiler will last longer than you are willing to run it.

 

[Bad LP]

IMO A Buderus is a cast iron boiler, unless it was major abused its got a lot of good years left. The Riello burner is also a fairly well known unit and parts are available.

As for heat load calculations you are running into rules of thumb. In theory on the coldest day of the year the boiler should have just enough capacity to keep the house at design temp while supplying a full hot water load (if the boiler supplies hot water. In that case of the coldest day, my guess is you would accept turning the thermostat down in the shop to free up heat for the rest of the house. The reality is a boiler is set up to have extra capacity to deal with things like cranking up the thermostats at the worst time or dealing with sudden heating demand like leaving a door open in very cold weather. Burner nozzles can be downsized a bit if you go too big but once you hit the boiler surface area you really can not get more heat. (Note buried in the calculations is fouling factor. I think Buderus boilers are three pass units and they need to be cleaned annually as they can partially plug up and lose capacity. I have heard some speculation is that the switch to low sulfur fuel oil keeps the boilers cleaner.

So if you go small you are trading off some flexibility with the system, the house takes longer to come up to temp in situations like when you come back from vacation with the thermostats turned down. Go too big and the boiler can short cycle but you can have the tech put in lower rated nozzle (with in reason)

IMO Mass is going to be putting in major incentives to upgrade away from fossil fueled boilers and the cost of heating oil is going to be going up in the long run. Odds are the boiler will last longer than you are willing to run it.

MA may offer incentives but there is no way to remove people off fuel oil. In our own case 33 years ago the gas company wanted almost 40k to run a gas main to the property. Big boss said NFW so in a vault went a 4000 gallon oil tank feeding 3 boilers.

 

[peakbagger]

The Mass incentives will be to switch homes over to renewable electric heat supplied ostensibly from renew ably generated electricity. Fuel oil, natural gas or propane are non starters anymore in Mass. . Mass also grudgingly does support some types of biomass heating but its definitely a low priority. Froling just expanded their Precision Dried Wood Chip plant to supply the demand in Mass and Southern NH.