Retrofitting Existing Single Zone to Multi Zone HW Radiators

I'm in the process of converting the oil burner over to a coal hw boiler. Since I'll be replacing the boiler, I've also been looking at adding multizone heating in place of the current single zone that I have installed.

This Old House has a segment where they cut out the cast for the different zones and ran PEX with controllers to each individual radiator. From what I could see of this setup, it was all done with a single circulator pump. Which would be ideal for me. Ideally, I would like to have a zone for the bathroom (chilly mornings suck), all the bedrooms and then one zone downstairs.

The house is a center hall colonial, two floors ~1500 sq ft of living space. 4 rooms up, each with one radiator and one in the hall. Two room on the lower floor, each with two radiators. All located under windows, and with the oil burner there's plenty of heat when I turn it up (which is never ). I'm pretty well insulated with storms all the way around.

Eventually, since I have access in the basement, I'll be running a multizone radiant heating system downstairs. Upstairs, I'm stuck with the radiators unless I start pulling up the floors (not an option) or reducing headspace.

So, has anyone made a conversion from single zone to multi zone in this manner? Since it looked easy, I'm assuming it won't be, but if it's not hideously expensive, I will be giving this a shot.

Thanks for the input.

There is a way to make each of your radiators a "zone" without repiping. It's called a thermister (I think) valve. Someone here will know the details. They use them in Europe extensively.

You must be thinking of a thermostatic radiator valve. A thermistor is an electronic component, a resistor that changes value proportional to temperature. Danfoss is one of the popular radiator valve brands. See: http://www.danfoss.com/

kstills wrote:I'm in the process of converting the oil burner over to a coal hw boiler. Since I'll be replacing the boiler, I've also been looking at adding multizone heating in place of the current single zone that I have installed.

This Old House has a segment where they cut out the cast for the different zones and ran PEX with controllers to each individual radiator. From what I could see of this setup, it was all done with a single circulator pump. Which would be ideal for me. Ideally, I would like to have a zone for the bathroom (chilly mornings suck), all the bedrooms and then one zone downstairs.

this is a good plan - just expand on what has already been done

kstills wrote:The house is a center hall colonial, two floors ~1500 sq ft of living space. 4 rooms up, each with one radiator and one in the hall. Two room on the lower floor, each with two radiators. All located under windows, and with the oil burner there's plenty of heat when I turn it up (which is never ). I'm pretty well insulated with storms all the way around.

Eventually, since I have access in the basement, I'll be running a multizone radiant heating system downstairs. Upstairs, I'm stuck with the radiators unless I start pulling up the floors (not an option) or reducing headspace.

Your not "STUCK" with radiators -- your blessed - they will give you a very similar comfort and economy once you balance the individual flows to each.

kstills wrote:So, has anyone made a conversion from single zone to multi zone in this manner? Since it looked easy, I'm assuming it won't be, but if it's not hideously expensive, I will be giving this a shot.

Thanks for the input.

Did it in my little place -- currently have a reduced temperature loop with three zones on it for infloor and a boiler temp loop with 18 zones - two small pumps run the whole business - there is another pump to introduce energy from the pellet boiler and the NG boiler is on line at all times to pick up on failure of when the degree day load is too heavy for Baby Boiler.

Go for it! I have 75 degree bathrooms - 50 degree entryways and unused areas - hi 60's comfortable sleeping temps - and low 70 in my kitchen.

Sting wrote:

kstills wrote:I'm in the process of converting the oil burner over to a coal hw boiler. Since I'll be replacing the boiler, I've also been looking at adding multizone heating in place of the current single zone that I have installed.

This Old House has a segment where they cut out the cast for the different zones and ran PEX with controllers to each individual radiator. From what I could see of this setup, it was all done with a single circulator pump. Which would be ideal for me. Ideally, I would like to have a zone for the bathroom (chilly mornings suck), all the bedrooms and then one zone downstairs.

this is a good plan - just expand on what has already been done

kstills wrote:The house is a center hall colonial, two floors ~1500 sq ft of living space. 4 rooms up, each with one radiator and one in the hall. Two room on the lower floor, each with two radiators. All located under windows, and with the oil burner there's plenty of heat when I turn it up (which is never ). I'm pretty well insulated with storms all the way around.

Eventually, since I have access in the basement, I'll be running a multizone radiant heating system downstairs. Upstairs, I'm stuck with the radiators unless I start pulling up the floors (not an option) or reducing headspace.

Your not "STUCK" with radiators -- your blessed - they will give you a very similar comfort and economy once you balance the individual flows to each.

kstills wrote:So, has anyone made a conversion from single zone to multi zone in this manner? Since it looked easy, I'm assuming it won't be, but if it's not hideously expensive, I will be giving this a shot.

Thanks for the input.

Did it in my little place -- currently have a reduced temperature loop with three zones on it for infloor and a boiler temp loop with 18 zones - two small pumps run the whole business - there is another pump to introduce energy from the pellet boiler and the NG boiler is on line at all times to pick up on failure of when the degree day load is too heavy for Baby Boiler.

Go for it! I have 75 degree bathrooms - 50 degree entryways and unused areas - hi 60's comfortable sleeping temps - and low 70 in my kitchen.

That's exactly where I see going with my house.

The kids are out now, and I have no need to heat the entire place unless they are visiting.

Can this be done off of one circulator? I've seen radiant flooring that seemed to use a circulator for each zone, but I have to imagine if you can hook up electronic valving that you can achieve the same result without going through the extra expense.

Oh, and I love the radiators for heating, best I've ever experienced. I meant that I cannot change them out without major modifications.

if your intention is to mix radiant flooring and cast iron radiation - you will need a temperature reducing loop or a thermal reacting valve to feed the infloor radiation - a lower amount of energy than to the cast - if you also mix in base board - you will need a third energy level supply loop

its all possible - but each temperature loop is best served by a dedicated pump

if you only dealing with one of these types - yes one pump (installed correctly) will operate the load just fine.