Plumbing OWB to indoor boiler

[Mjf3487]

I'm installing a used outdoor boiler to my indoor oil boiler. I will be using a heat exchanger. The Indoor boiler has a coil in it to heat domestic water and a single zone to heat the house. At this time I'd like to leave that alone

I'm thinking the simple option would be to add a second zone to indoor boiler and run circulator 24/7 through the heat exchanger. This should keep indoor boiler up to temp all the time allowing me to have hot water all the time and heat whenever the house calls for it.
The negative would be running 2 circulators 24/7.

Does anyone see a problem or possibly a much better option?

 

[hondaracer2oo4]

You could power the owb heat exchanger "zone circulator" when your house thermostat called for heat. You could put a strap on aquastat on the incoming owb line which would keep the oil boiler from firing unless the owb incoming line was lower than a certain temp say 150. That is how mine is set up but I have a primary/ secondary loop system with closely spaces tees but your zone off the boiler will work well.

 

[92rslt1]

Throw a side arm on the water heater and never look back. They can be had for very little expense, probably less then pulling a few amps 24x7 year after year. Or you could use an aqua-stat and just have the pump circulate when your water heater temp drops below a desired point. No point in circulating all that water to the water heater 24/7 for a few showers a day, when realistically the water heater is well insulated and will hold temp for a long time once its idle. Another thing to consider is that by circulating water that hot constantly through your water heater, you would need to add a anti-scold valve, its not even an option. So your best bet is connect it in a manner that will regulate the desired temp, while not wasting all that energy.

 

[maple1]

Throw a side arm on the water heater and never look back. They can be had for very little expense, probably less then pulling a few amps 24x7 year after year. Or you could use an aqua-stat and just have the pump circulate when your water heater temp drops below a desired point. No point in circulating all that water to the water heater 24/7 for a few showers a day, when realistically the water heater is well insulated and will hold temp for a long time once its idle. Another thing to consider is that by circulating water that hot constantly through your water heater, you would need to add a anti-scold valve, its not even an option. So your best bet is connect it in a manner that will regulate the desired temp, while not wasting all that energy.

He's talking boiler, not water heater.

 

[92rslt1]

My bad, I was under the impression he was taking about a domestic hot water loop.

looks like the proposition is to run the heat transfer loop through a zone?

Why not just plumb the hx into the return side of the boiler? Eliminate the need for the extra pump?

 

[maple1]

I don't think an extra pump would be needed in either case. But more heat would be drawn from the hx by cooler water entering it - which would be return water.

 

[Mjf3487]

My oil boiler has a coil in it, that's where I get my domestic hot water from.

I originally planned to run the hx into the return side but then it would only circulate when the house called for heat. During a shower I would run out of hot water, especially if the house hasn't called for heat recently.

I only have a little experience with boilers so maybe I'm missing something. I appreciate everyone's help

 

[maple1]

What you want to do should work - but when your other zones are calling for heat, you might not get as much heat to them as you want. The HX might not keep up, as a lot of flow will be going to zones. That's assuming you are using the same pump for the HX zone as the others. If the HX zone has a separate pump, don't think I'd run it all the time, but control it so it only runs when the indoor boiler needs heat. But that's your call - lots of OWB guys seem to run pumps 24/7 OK, but I likely wouldn't.

 

[Mjf3487]

That has crossed my mind.

The oil boiler and outdoor furnace both have taco 007's. That's what I was going to use to circulate the boiler as well.

I don't think I'll have trouble with heat, it's a single story house about 1200sqft and it's ran on a single zone