mod. cons. at 180*

Derheatmeister

It Depends on you heat emitters

I have found that most of them are "Oversized" and it will work good.

I have seen 30% to 40% savings due to Out door reset/ Modulation in milder outdoor temps!

Jim Wy.

Is it still worth it to use a high eff. boiler if the system uses B.B. @ 180* ?

steve_29

As has been stated, if you are over radiated, have CI BB or radiators you should be ok.

While ODR certainly has proven it's worth in savings, some owners complain about increased run times for circulators and longer times to get room temps to where they want.

Certainly this can occur as a result of setting back room temps in colder temps.

Mod Cons are designed for cooler supply and return temps, maybe your better off with something like a Systems 2000, where you have 180* water but a very efficient post purge feature.

Unknown

Yes!!

Yes it is worth it. The combination of modulation and condensing will increase your efficiencies. With 180 degree baseboard you will benefit more from the modulation. If you add reset into the picture it will get even better.

We design to set parameters. Example 10 degree outside temperature and 68 degree inside @ 180 degree water temperature. On warm days your return water will be much warmer and the modulation will adjust the boiler input to closely match the heat loss. This works better with a properly sized boiler and a system that is not over zoned. I do a lot of single zone constant circulation systems with a tight reset curve. If the boiler is oversized it will not be able to modulate low enough to have any benefit.

One other thing I like is that you eliminate your combustion air requirements and chimney with a Mod/Con and indirect setup. This will help with your infiltration.

No need to add a chimney liner or expensive SS venting.

Just my opinion. I stopped using traditional cast iron boilers for hot water applications around 2000.

steve_29

While I don't diagree that during cold temps, water temps will reach 180*, the problems generally occur during warmer outside temps.

Some people are more sensitive to the cold and cooler water circulating doesn't radiate like 180* water would.

I don't believe a ModCon is a fits all for every apllication.

How large are these homes your doing with single zones?

Unknown

Single Zones

Not large. Typical 1500sf to 2000sf homes. Quite a few older homes with radiators.

The constant circulation evens out the room temperatures.

Unknown

another note.

Just completed a boiler install on a hacked system. Previous owner mixed radiators and baseboard. Living room and dining room were always cold due to the copper fin board. Owner was on tight budget.

Ran that system single zone constant circulation and no more cold living room/ dining room. No need for added zone valves, circulators, or thermostats.

Unknown

BTU's

"cooler water circulating doesn't radiate like 180* water would."

It is still giving off the same amout of btu's to acheive the same room temprature warm or hot.

steve_29

Interesting

Am I correct, that all you did, was to run the circulator to that area all the time? Does the circulator run even during the non heating season?

Unknown

not correct.

Not correct. Circulator runs whole house 24/7 during heating season only.

steve_29

Oh, you only use 1 circulator.

It originally had seperate zone?

Outdoor temp. controls circulator?

Unknown

one zone.

The existing system was single zone one circulator one pupmp Oil.

The base board would cool off quick the radiators would stay hot. Thermostat was in living rooom with baseboard. whole house was always cooking. Living room and Dining room were always cold.

Simple constant circulation resovled the issues. One system circulator and one boiler circulator. Boiler pipeing is set up as per manufactures install injecting into system through closly spaced tee's.

steve_29

I was always under the impression that warmer water contained more BTU's than cool water.

I was also under the impression that an under radiated room may never achieve comfort when heat loss was larger than gain.

Unknown

Oh Boy:)

Well if the room only needs 10,000 btu's of heat and the heat transfer medium has 20,000 btu's or 80,000 btu's it is still only gonna transfer 10,000 btu's.

Rite on with the under radiated room. What is the next test gonna consist of?

Unknown

Photo.

Found this picture of the job. Vent was not glued in photo. The V-500 Vent was back ordered and did not come til the next day. I glued/primed and did combustion test the next afternoon.

rich pickering

issue is...

the radiating device (CI radiator, Fin tube baseboard, other) will radiate/convect less heat if the water's cooler. If the radiator or baseboard's oversized enough (quite likely, but not certain) than it will give off enough heat anyway.

Put another way the water will give up the same heat, at a fixed flowrate, going from 180 to 160 as from 140 to 120, but the radiator/baseboard will give up more at 170 average than 130 average, so a bigger radiator/longer baseboard will be needed in the second case to achieve the 20° delta.

Unknown

cold room.

if the room is cold the radiator will give up more heat. if the room is hot the radioator will give up less as it aproaches indoor design temp.

tim smith

The biggest problem I see with mixed radiation is that cast has

such a long cool down rate and the fin tube cools really quick due to low mass. Once you go to constant circ and reset then you can better match the two outputs as you take the cool down rate out of equation as they are always on and heating. Still don't like mixed radiation but this is a way to help solve a botched install. Tim

Unknown

Not true.

If your water to room delta T is higher (higher water temperature) you will transfer more heat in a SET ON CYCLE than you would at a lower water temperature. If both are on for an hour, for example, the high temp might transfer 15kbtus and the low temp 10kbtus.

But this means you will cycle OFF faster. While it is on, the owner will notice the hot radiator/radiation.. ooh, warm. Then it turns off. oooh, cold. rinse and repeat. the problem is many people are psychologically expecting oooh, hot, when the heat is on. and frankly, as a guy who grew up six inches from a wood stove, some people like a burst of intense heat to "soak up" sometimes.

Perfect reset curves, as you know, are not generally noticeable heat. you don't get, "ooh, warm". but you also don't get "ooh, cold". it's just hmm.. comfy. That's nice and good, but it's not the same as "ooh, warm".

I think what you meant to say was that as long as you are providing the BTUs needed, you can provide good comfort, and that heat loss doesn't change.

Xc8p2dC

Lots of flexibility

First, you will probably not need 180° water

Second, It is true If you run lower water temps, recovery can take longer, but

Third, the benifit of a MC is to be able to control, If you pick the right one and know how to control it, you can change parameters and curves to compensate for shoulder temps, to get quicker recovery

Forth, pay no attention to DeltaT's, that a CI thingy, ModCons operate on different principles when contant circ

Let the arrows fly>lol