I agree with Richard - I hadn't properly digested the full extent of the problem and my solution was only an answer to the problem of stopping the calorifer receiving a slug of cool water - which it would do, however it will not prevent the problem of the boiler water boiling because there is insufficient circulation in the system from start up.
Bru > -----Original Message----- > From: [email protected] [mailto:[email protected]] > On Behalf Of Electricky Dicky > Sent: 02 February 2009 07:57 > To: [email protected] > Subject: [canals-list] Re: Plumbing parts > > On Sun, 1 Feb 2009 18:44:29 +0000, Kennet Boater > <[email protected]> wrote: > > >Hi Brian and Richard > >I have fitted an overide switch so the pump can be switched from > thermostat to constant to prevent the 'boil up' as the fire initially > gains heat. (The boiler fittings are small and don't allow the heat to > travel the pipe and start the therostat before boil up) > > > >Once the system is hot I switch back to theromstat (set low to avoid > boil up) and all is fine. > >We burn wood rather than coal so when the fire dies down (if we are > slack at 'log chucking', go out or go to bed) the pipe seems to get > very cool before the thermostat cuts out. > >Im not bothered by the rads getting a spell of cool water but the > calorifier looses a fair bit of heat. > > > >What how does the thermostat on a older type car work? Would that > stop/allow water along a pipe. > > > >The system is on my refit boat so the pipe thermostat is less than a > year old and has only been used on and off (ha ha!) this winter. > > > >Currently fiddling with the pipe stat settings but its as long job as > envolves a full cycle of cold/hot/cold. Would like to have the > calorifier only receive the hottest water, without me having to go > wardrobe potholing each day! ho hum! > > > >Thanks for your suggestions > >Lee > IMHO you have a basically crap control system! My initial reaction to > your original post was "Just get a Thermostat with a smaller switching > differential". However this subsequent post has indicated that is not > enough. > Your comment that "I have fitted an overide switch so the pump can be > switched from thermostat to constant to prevent the 'boil up' as the > fire initially gains heat." is the killer. > No external system whether mechanical as Bru has suggested or > electrical will handle the problem as described. > > IMHO you need to get a low differential thermostat that monitors the > Boiler water temperature, only then will you have a safe workable > system. If you cannot monitor boiler temperature directly then you > need to change your "Hot" outlet configuration so that you get some > rise from the boiler before circulating. Given a vertical pipe the hot > water will rise to that area with or without the pump. The stat should > be fitted to that vertical pipe. You do need a reasonable diameter > pipe to ensure gravity circulation in that area. > > Ensure that your header is higher than this vertical, fit a vent at > the top. Sorry but I have seen this problem before and the above bis > how I sorted it. Problem is it is difficult to make it look "pretty" > <G> > > > > > -- > Richard > > > ------------------------------------ > > Yahoo! Groups Links > > > > No virus found in this incoming message. > Checked by AVG - www.avg.com > Version: 8.0.233 / Virus Database: 270.10.14/1920 - Release Date: > 01/27/09 18:15:00
