condensate from mod/con

Unknown

has a mcba control with a outdoor reset control built in. However many installers dont connect the outdoor thermister. There are several reasons for this, some just dont understand it. Another is the fact that Triangle will only give installers full access to the parameters in the mcba control after they have finished the factory training, otherwise you only have access to the first 4. That will let you connect the outdoor reset but it will not let you activate the boost system. So you can see the problem that many installers have. As long as the outdoor reset has a target temp below 135 you should be condensating. You will get about 1 gallon of water from every 100000 bts of gas or 100 cubic ft. so by clocking your meter you can easily see if your close.
TONY

Eileen Olive

condensate from mod/con

I have a new TT Solo 110 which seems to run fine, but it does not condensate very much. My delta T is roughly 21*, when running (supplu 168, return 146) after running about 20 minutes, outside temp is about 27* I seem to get 6 gals every 2 days, I'm draing into a large bucket prior to dumping the condensate. Does this seem to be too little? My emitters are CI radiators, and I am in the subs of NYC. Might I gain by adding a radiator or 2 in the basement, to warm the basement, which will heat the firt floor flooring, and reduce my return temp?

mark_121

Temps. to condense

Under average conditions condensing happens in a boiler at 135F and under. With Mod/Con boilers a temp above this will yield little condensation. My thoughts are when your boiler calls for heat your system temp water is below 135F witch will yield condensation with time your system rises above that magic 135F and condensing is no more.
In most cases you can lower your system temp and run your boiler longer. It will not hurt your wallet any, the idea is to match BTU in to BTU loss of the house so you only pay for what heat is radiated through your structure. If your boiler has a outdoor temp monitor your boiler should ramp back to do this or just set your system temp back and play with it till your system cant heat your house then you will know where the breaking point on temp is.
In science things in motion like to stay in motion. hence a system that runs all the time uses less energy when equilibrium is established. I think your system temp can maintain your house at 135F or lower allowing your boiler to condense and costing you less to heat.

tim smith

Depending on amount of radiation vs heat loss, you may

be able to run lower water temps and stay in condensing mode much more. Your water temp now is not going to yield much. Would be a good idea to calculate heat loss, zone by zone and then figure what the output is of existing radiation based on water temp. Then you can calculate what water temp you can get away with. Tim

Brad White_202

Too High a Temperature

Use The Force, Skywalker... Outdoor Reset.

In "warmer than design" cold weather like we are having, you should be running water out of the boiler at probably halfway between your high and minimum temperatures.

In other words, if you require 180F water on the coldest day (say 0 degrees, I do not know where you live), you would need 125 degrees when it is 35 degrees outside. That will get you condensing nicely.

Fact of the matter is, most houses have more radiators than they have heat loss. For example, you might only need 150 degrees on the coldest day. Thus if it were halfway between, say 35F outside, you would only need 110 degree water. Condensing is assured.

Basically, you want your return water to be 120F or lower for full effect. The "135 F" rule is a safety zone to prevent condensing in non-condensing boilers. It allows some room for safety. When you want to condense, colder is better, so seek it.

My ideal design point for new construction or where I can control the radiation to heat loss ratio, I design for 140F supply and 100F return on the coldest day. An average day thus uses 105 to 110F supply water and condenses across the entire range.

Give ODR an adjustment suited to your radiation/heat loss ratio!

Brad

Eileen Olive

Purchased the ODR but . . . .

After reading the included instructions, and trying to adhere to it as closely as possible, it is still in the box. Just watched DIY on TV, watching them install an ODR and I decided to just do it. The instructions from TT say to install the sensor halfway up the house, while DIY installed it alongside the electric meter. So I figure I'll get as close to halfway as possible. But as for adjusting the curve on the ODR, I guess I will have to call TT to get the lowdown. Thanks for the advice.