The weldment is the firebox and water jacket(every thing that touches fire or water). The ashpan is the fire brick and ashtub it's almost all under the sand. I can't say what Heatmor will do every time just what they have done on the few times we have need warranty. And that is that has been more cost effictive to replace the whole unit. When a Heatmor goes down they and we want it back up and running as fast as possible this has ment, replace the unit asap. To build a weldment or ashpan and ship it would take to long. There were No Charges to the customer. Now there are parts that can be replace the inner door, fans, firebrick, bladder, aqustats or fire grates. A Heatmor is very easy to work on, if the custom wants a service call for these part there could be charges. For us to go say 500km to change an aqustat yes I would charge for the trip but we run Western Canada, some dealer with a smaller area may or may not charge for that. A customer that has never change an aqustat before should be able to change it in less the 15min. Heatmor has what I would say is by far the best warranty of any outdoor wood furnace this is the main reason we took on the brand 13yrs ago. The first 5yrs is a 100% covered on the weldment and ashpan and after that it is prorated. But I must point out that in 13yrs we have only had 9 units fail in all of western Canada. I've had one pump and one aqustat go on my unit at home in the last 7 yrs and 1 pump go on the unit at the office in 13yrs.