View Full Version : converting to 2 ZONE heating need help

01-20-2010, 07:13 PM
I am trying to convert to 2 zone in my house the heating used to be two zone but somebody converted it to 1 zone so I am trying to go to 2 zone heating. It is oil heating, and the pic show what I have now I also put diagram to help out if anybody can help with what should I do to switch to 2 zones.
Any help would be nice

Peter Griffin
01-21-2010, 03:21 AM
do you really want to put any money into that thing? It has to be 60 years old at least. Looks like the system was probably a steam or gravity conversion. At a minimum you have to re-locate the circulator and install either another circulator on the other return line or a couple zone valves on the feed lines along with either a circ relay or a transformer for the zone valves. You also need to be sure the piping does separate into two distinct loops. Personally, I would tear that beast out and replace it with something that gets better than 45% efficiency.

01-21-2010, 08:24 AM
So I should just go with whole new system probobly gas??
Also should I go with tankless on it, once new system is instaled, can I have tankless if I am having radiators in my house?

01-21-2010, 11:46 AM
Definitely looks like a conversion from steam, with a small DHW coil that red ~5 gallon buffer tank on the boiler bypass.

Scrap the beast it's probably oversized for the load anyway, and guzzling 1.5-2x as much fuel as newer-better stuff would. Go for something gas-fired & lower mass, maybe "high efficiency" condensing, maybe not, but DO make sure a careful heat load analysis is done, and that the boiler isn't oversized for the heat load or you'll pay for it in fuel every year.

Rather than an embedded tankless coil for the hot water, get an indirect-fired tank operated as a third zone with "priority" control. It'll put out way more hot water at much higher efficiency than a tankless coil embedded in the boiler (or the tiny coil in that red bucket you have there.) If one of your zones is much bigger than the other (like 3-4x as big), you might be better off using a "reverse indirect", buffer/heat exchanger from which the zones draw, with the boiler set up on it's own loop. Otherwise the boiler would short-cycle on the smaller zone, which will rob it's efficiency. A buffer in the middle sort of averages it all out the same way high-mass boilers do, but with much better insulation they have lower standby losses. A buffer with an internal heat exchanger for hot water is less expensive than a separate buffer + indirect tank.

Also, when setting up a new system with the full heat load analysis in place, set it up to run at the lowest temperature that delivers enough heat to the coldest room on the coldest day (or use responsive controls that sense outdoor temps and raise/lower the water temp as needed). Every 10F you lower the water temp in a hydronic system saves ~3% in fuel use. If it's set up for 180F, but could deliver the heat at 150F you're burning 10% more fuel than you need to. If it can deliver the heat at 140F or less, that's when a condensing boiler will really save a lot (25-35%), when combined with outdoor temperature sensing (a feature built into most condensing boilers.)

01-21-2010, 12:43 PM
Thank you so much, I have a gas company come next week to check and give me price, and I can ask them all the stuff that u told me, great help thank you.
Def going to gas, thank you all
I will post pic of new system once instaled