Tired Of Explaing Design Temps

Gordy

The other part of the equation. Envelope is another also. But the installer should know what they are up against if no improvement is going to happen with the envelope, and they did the math.

Gordy

Unknown

In my area,

I typically use -10F as design, so of course I size accordingly.
Because of the brutal cold we`ve had the last few days some people are calling because their room temps will only hit 68F with the boiler running full-tilt.
Automatically they think I undersized it, I`m getting tired of the lengthy explaining I have to do AGAIN to convince them otherwise.
Anyone else have this?

Dave

Alan Hendrickson

I wish my boiler had been sized that way. I think it was done using a -68 F design temperature. It was -16 here this morning and it was still short cycling and maintaining setpoint. I might as well be burning dollar bills.

Wayne_29

The Northeast Design Temp

Today went to -20. Has anyone heard from Al Gore about this?

Charlie from wmass

We use -20 for our design temp in western MA. We also figure 180 degree water. THis leads to slightly larger boilers and more radiation for a given space. It also means we can use outdoor resets and use lower water temps on the none design temp days. I have also noticed despite the debates concerning over sizing it usually does not mean that large of a boiler as there are not that many choices in size. If I lived closer to the shore or further south I would use a warmer design temp. The thing is we do not get calls for rooms only gettting to 58 when it is -20. With the use of outdoor resets we also do not get compllaints of short cycling. Every year we get at least a week to two weeks of close to -20.

Mark Custis

Charley

At 180*F are you specing emitters?

Mark Custis

Charlie

At 180*F are you specing emitters?

Charlie from wmass

180 degree water for perimitter baseboard and wall hung rads. Obviouslly not for radiant heat systems as I don't know about you but I do not like my toes that hot.

Mark Custis

Not that hot

Just a question. Now that I know how to do this stuff the body is not as willing. I am looking at the idea of adding emitters to lower the high temps and still deliver the BTUH.

don_201

Back on topic

Below design temps, everything suffers.

Ground source heatpump, after all the earth emitter has it limits too.

I'm sure you guys that are using closed loops without a backup boiler have to be experincing lockout problems.

Humidifiders.Even the steam one are doing all they can do.

Just wait,I'll bet in another eight months we'll get to say..sorry we're above design temps.

Gordy

Last time of below design temps.

Dave, Have you tried pointing out the last time below design temps occured in the area?

For me here in the midwest its -10 also. The last time we were below design temps was 84 then 78/79 winter which was in the -20 to -25. Before that. It was the mid 50's.

The reacurance is not that frequent, or for a very long duration. Here it lasted a few days this time around.

I think finding the boiler with the sweet spot in its modulation if a mod/con, or conventional to cover the heatload plays in to it. Sometimes its right on, sometimes you have to go a size up because the next size down is to small.


I don't think 68* running full out is a big problem, but then again no one complains if there is not a lack of heat.


Gordy

troy_8

Underdesign

Boiler size is only one piece of the equation. These temps. separate the good from marginal designs. In my area we always use aluminum plates when installing underfloor. This is when the tube only guys are not answering their phones. I got a call from a women who wanted a second opinion on why she can't achieve more than mid 50s when it gets cold. She claims this has happened every year since install. Installer wants to increase water temps over 180deg. says that will provide more heat. Sure will. Sorry hardwood! Floors must be defective. If our standards don't go up then we as an industry deserve the fate that awaits us. I don't advocate oversizing boilers or undersizing emitters. Th achieve the greatest potential of a high efficient boiler you had better oversize your emitters.

Unknown

I hear ya Troy

This job was done by a competitor a couple of years ago.
I wonder how he faired with the recent cold snap.
One can imagine.

Dave