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my re-started radiant system

ALH_4 Member Posts: 1,790
I recommend installing a <a href="http://www.tekmarcontrols.com/literature/acrobat/d260.pdf"target="_blank">Tekmar 260</a> outdoor reset control to lower the water temperature. At that point the aquastat setting is only a high limit.


  • i've not used it for a year

    and this post will consist of several questions, but to try to keep it simple, i'll only start with one

    i'm using an old h-well a-stat, L8148E, and i'm wondering;
    it's lowest temp setting is 180degs, and it's on my little old ci burnham, an '83, p-206-w. is there a reason against using another a-stat that allows me to run a lower boiler temp? my 2 zone/loop temps work well at 120degs and 130degs, controlled by taco mixers

    and i might add, using my heat pump set at 68degs, i keep a t-shirt and long sleeve shirt on all day. using my radiant for 4hrs, i was comfy with only my t-shirt
  • Rich L.
    Rich L. Member Posts: 414

    You can safely run your cast iron boiler at 140 degrees and avoid flue gas condensation while saving energy $. Your mixing system will still mix down to the 120 - 130 degrees you need for your system.
  • excellent, thank you

    my concern was the flue gas condensation, and eating a lot of lp. but i should also add that i have a tjurnland power venter on the boiler. does that matter?
  • hot_rod
    hot_rod Member Posts: 21,872
    140 return temperature

    you need to assure the boiler stays above dewpoint. With an conventional cast iron around 140F.

    Some controls have a return temperature sensor to assure the boiler never drops below that critical temperature, for extended periods.

    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • so, a control like the tekmar

    will keep a balanced boiler firing in relation to the outdoor temp; ie, no short cycling due to running out of hot water, and not having the boiler firing up to 180, even if it provides hot water for a longer period of time, therefore longer non-firing?
  • and......

    after putting new o-rings in the tacos because of leaks due to inactivity? and 'dirt', i completely flushed the system until i had relatively clean water exiting my drain hose

    after calculating and pressurizing my d-tank's pressure/ highest point of piping to be 5psi, i filled my system to 5psi and started the boiler. chatter-chatter-chatter said the main pump. oops, i hadn't oiled it. oil-oil-oil, all quiet for about 30mins. back to chatter, and my heated pressure rose to 15psi. pulled my pt-valve and blew off a big whump of air from the top of the boiler, and bled some more from the purger/air vent. still chattering. added a tad of water, to 18psi, the chattering stopped. i let the system run until the house was nice and warm, and then shut it down for 18ish hrs

    came home today to a cold system, and 10psi. bled off some water until i had 5psi again, and fired the boiler. it's up to temp, the boiler has fired several times to 180degs, my tacoed zones are at 120 and 130, and my pressure is back up to 16psi with no pump chatter

    does this all sound normal?

    and as of this morning, 3-11-08, my system has cooled and holding it's 5psi
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