Nothing gets fixed for free or at a loss, the guy who quoated £190 probably knows that most faults are fixed with in the hour (say £60 / Hr) and an average part would be £130. Unless that is the system is clogged up, or something drastic is wrong with it.... but then the engineer should know this quite quickly and estimate what the cost will be. Giving you the chance to consider if its worth pumping money into the boiler or replace it for around £2,ooo (London prices, anything a lot less and you need to ask why!!!)
Sherman Heating 8579 2561 Ealing Area Only, July 2006