plumber

maxflow

one person living in large 4  bed room  house would like to zone, says "to much  heat-money being wasted". seeking best method of heating spaces occupied while keeping rest of house from freezing,  Existing crown 100,000 + BTU gas fired boiler, old style free standing radiators and one thermostat control.  

kcopp

sounds like a perfect.....

fit for TRV's and an grundfos alpha pump. Each rad is its own zone and the circ can adjust the flow acordingly.

http://www.radiatorcontrol.com/

http://net.grundfos.com/doc/webnet/poweredby/gpu/US/alpha.html



kpc

Brad White

How much re-piping do they want to do?

If the goal is to keep bedrooms cooler (five degrees to me is a minimum zone differential but everyone is different), this is entirely practical to do.



Some different approaches:

1. Group the pipe runouts to the specific rooms which want to be kept at a lower temperature and give them a master zone valve. Group the remainder, the "core" zone for daily comfort, on another zone valve.



Have all circulation done by a VS circulator, be it a Wilo Stratos Eco, Grundfos Alpha or, once the Buzz settles, the Taco Bumblebee. The first two are delta-P responsive, the Taco Bumblebee is delta-T responsive. I have done both strategies, both work great, the delta-T makes the pump run slower though, not a bad thing. 



Upstream of this, install a full range outdoor reset mixing valve (Taco i-Valve is a good value, Tekmar and others are similar and with more features but higher cost.) Point being, control your water temperature for the full range, from what you need on the coldest day to maybe ten degrees above room temperature.



Then, put the boiler on an outdoor reset control limited to a range of 140F to 180F low to high as a final touch. The Taco PC702 is a good value also, made for them by Tekmar.  With all of this, the radiation will "sip" boiler water as it needs it. With one zone calling, the boiler mass will hold the heat between firings and the automatic differential will help with any short cycling.



2. Cheap down and dirty but possibly more work:

A. Put TRV's on all the radiators. If the unused rooms are seldom used, set the valves on the "snowflake setting" or way down to suit.  Set the comfort rooms as you like them.



B. Go with the mixing valve and boiler ODR if you like, but forgo grouping the piping into zones. Each radiator becomes a high limit zone anyway.



3. Combination of the above. TRVs on radiators with grouped zones with master control valves to give the seldom used rooms a chance to "call" independently of the master zone.



Lots of ways to go about it. It gets down to cost, value and expectations.