Run the Circulator 24/7 or on Demand?

As most know I'm putting a water to air exchanger in the furnace duct work, and probably a modine in the garage, I already know the circulator I have will handle both exchangers, the question I have is should I run it constantly or have it cycle with the fan. The difference will be if only one heat exchanger has a call for heat I'll have to put in zone valves to stop the flow to the other heat exchanger if it's a waste to circulate the water without the fan running?

hotblast1357 wrote:As most know I'm putting a water to air exchanger in the furnace duct work, and probably a modine in the garage, I already know the circulator I have will handle both exchangers, the question I have is should I run it constantly or have it cycle with the fan. The difference will be if only one heat exchanger has a call for heat I'll have to put in zone valves to stop the flow to the other heat exchanger if it's a waste to circulate the water without the fan running?

You will be throwing away (or at the very least, misdirecting) heat energy if you circulate constantly. The boiler will likely fire more often than need be.

Would it cut back on overfires?

So what if I have it wired to both thermostats, to pump when there's a call for heat, then the only time I'd be wasting heat is if the houses call for heat and the garage doesn't, or visa versa. It would save me about 250 dollars in two zone valves.

hotblast1357 wrote:So what if I have it wired to both thermostats, to pump when there's a call for heat, then the only time I'd be wasting heat is if the houses call for heat and the garage doesn't, or visa versa. It would save me about 250 dollars in two zone valves.

Money saved up front will evaporate into losses over time if you annually have to buy more coal than you would for an optimal setup.

This is true, I guess I would have to figure out how many BTU's it would pull from my boiler to circulator through the heat exchanger without air blowing through, once it's cold enough out I would be surprised if at least one of them wouldn't be calling for heat at any given time, remember the garage is going to be wire for the dump zone also. If I do end up with a lot of "dumps" the thermostat in the garage will barely ever call for heat too. I might not even put a thermostat out there, if I'm going to be dumping that often.

If money for this project is so tight look for less costly discounted parts.
Fancy controllers can be assembled ala carte for savings over "all in one" controller, and again with discounted parts.
Remember, you did get the boiler discounted.

What controllers do I need? I just don't see the point in wasting money if I don't have too, that's why I'm asking, I could just buy a pump for each zone but I don't need that, so I'm just trying to figure out how else too plumb it.

Just cuz I bought something at a fair price doesn't mean that I now have thousands too spends on pumps and zone valves and fittings.

Controls for how ever many pump(s) or zone valve(s), need 24 volt t'stat(s) to start/stop 120 volt pump(s) or 24 volt to open/close 24 volt zone valve(s).

This hydronic system design layout has been done for many, many years...you're not the first.
Many good books on hydronic heating out there.

Alright so far in my head I've came up with a two pump system, I just have to do more research on it.

hotblast1357 wrote:Just cuz I bought something at a fair price doesn't mean that I now have thousands too spends on pumps and zone valves and fittings.

Whoa!, Think you missed my point. You said $250.00 for couple zone valves...so I thought for you to save money, do not pay for new/retail ones, get discount. Goes for everthing else you need.

Discount parts will work well on discount boiler...save some bucks.

We're here to help.

Ok I get what you mean now, my bad, have just heard some grief about things lately. I've shopped around but I don't know all the great deal places, cheapest zone valves I could find were 119 a piece.

No, you do NOT want to run the pump 24/7. That's for those OWB's that can't control there heat output and don't want there pipes to freeze in the ground. You only need a pump to turn ON when there is a heat call, or if the boiler is overfiring and the water temp is to high. When the is no heat call the boiler water will flow through your boiler bypass circuit to even out the boiler temp.

One way to control this is the good old Honeywell aquastat. There are more moden ways to do it i'm sure, but the aquastat is the old tried and true heat switch. The aquastat will take a 24 volt thermostat input and will turn the pump ON when there is a heat call from the thermostat and the boiler water is up to temp.

If the blower comes on with the thermostat, you could be blowing cold air around. The furnace blower should only turn ON when there is heat in the coil. So, some sort of aquastat should be on or near the coil to sense the heated water flowing through it. Thats all you need to control the blower. The blower doesn't need to know what the boiler is doing, only that there is heated water in it.

As McGiever said, you have some time so, find this stuff at a disscount. No need to pay full price.

-Don

HB, I have my shop circulator on 24/7 when the weather turns cold,this constant circulation thru both shop exchangers keeps some radiant heat effect going on & allows HOT air when the t-stat turns the exchanger fan on. I know this is totally wrong according to the professionals on here,but this has now kept my shop comfortable since 2006.When I open an overhead door & have a cold air flush sweep the shop,i don't want to wait for the exchanger to warm so the aquastat can allow the fan to run & blow heat around. This setup allows instant HOT air.