inexpensive diy mini-split install

[stuart1648]

Anyone know of a simple btu heat sizing chart that would involve these parameters:sq ft to be heated, temperature rise, insulation quality ?
Frankly, since Ive already got a 9000 btu inverter and know the area is about 450 sq ft. and january heat rise avg needed is about 25 degrees(W.Washington)Im mainly interested in deciding how good insulation I need.
Yes, I know about Manual J etc but this on the very low end of the heat pump hit parade. Thanks

[S-F]

Originally Posted by stuart1648

Im mainly interested in deciding how good insulation I need.

10, 20, 40, 60 - slab, foundation wall, above grade wall, ceiling. Then think about manual J and heat pumps and other mechanicals.

How much do you need? Well, none. The Japanese use very little and have the longest life expectancy.

[AC_Hacker]

Originally Posted by stuart1648

Anyone know of a simple btu heat sizing chart that would involve these parameters:sq ft to be heated, temperature rise, insulation quality ?
Frankly, since Ive already got a 9000 btu inverter and know the area is about 450 sq ft. and january heat rise avg needed is about 25 degrees(W.Washington)Im mainly interested in deciding how good insulation I need.
Yes, I know about Manual J etc but this on the very low end of the heat pump hit parade. Thanks

For the most part, the folks on this blog take energy efficiency and infiltration prevention and insulation pretty seriously.

Most of the folks here would consider insulating to state code as being the starting point, where the real fun begins... and going beyond the minimum is the whole point.

In fact, there's even a friendly energy efficiency competition going on here.

The information you have provided is insufficient to estimate anything... you probably don't realize it, but it borders on insulting in its incompleteness.

You might do better to telephone your local state energy department and ask her, or him, what the state code is for what it is you want to insulate.

Your rep will likely ask you questions about the information you did not supply in your request, above. Your rep will cheerfully do the work for you.

It's your tax dollars at work...

Good Luck,


-AC

[MN Renovator]

It only gets down to 45 degrees in west washington. ...or have I found someone else who is comfortable in a house that most people would ask if the furnace was broken upon entering? At 45 degrees I didn't even run my heat when I had insulation and air sealing done the same way that other mid 80's houses were built. I've since upgraded various bits of insulation and substantially air sealed since then. If you build to todays code and you only get to 45 degrees outside, I'm not seeing you needing to go above code to use a 9k inverter heat pump.

In the long run, you'd be better off not sitting at the minimums though.

[AC_Hacker]

Originally Posted by MN Renovator

It only gets down to 45 degrees in west washington.

Only gets down to 45 degrees?

What part of western washington do you live in?

Even this chart for Seattle doesn't tell the whole story... it's only average and doesn't display the spikes which need to be accounted for in determining 'design temperature'.

This average temp chart for Portland (my fair city)...

...doesn't reflect the fact that the temp dropped down to the high 20's this past winter, nor does it reflect the fact that temps dropped down to 17F last winter, nor does it reflect that thirty years ago, it dropped down to 5F and stayed there for nearly a week.

How long have you lived in the Pacific North West?

Are you aware that we get periodic severe weather that comes howling down from Alaska and Canada?

You are in for some surprises, my friend!

-AC

[MN Renovator]

I said that based on the OP's comment about 25 degrees indoor/outdoor differential. I may have read that wrong though. If 36 degrees out and 61 in is acceptable to the OP, then I suppose that is fine.

FWIW, I have a Manual J that says that at the absolutely coldest temperatures that a gas furnace or whatever the heating source is shouldn't be able to keep up and should sag down slightly in temperature in order to be more efficient for the majority of time that it isn't the coldest few days of the year. You'll never find an HVAC guy actually even try to explain that to anyone so they'll oversize the s*** out of everything. ...with inadequately sized ductwork sized more appropriately to the actual heat load while they are at it.

[AC_Hacker]

Originally Posted by MN Renovator

You'll never find an HVAC guy actually even try to explain that to anyone so they'll oversize the s*** out of everything. ...with inadequately sized ductwork sized more appropriately to the actual heat load while they are at it.

... a prioblem for fossil fuel, a big problem for vapor-compression machines.

-AC

[AC_Hacker]

But it still does not account for where you came up with the wacky statements about the weather?

I'd really like to know...

While you're mulling it over, HERE IS A LINK to a page with some fascinating Portland, Oregon outlier weather stories for your amusement. You can be confidant that if it got this cold in Portland, Western Washington was even worse...

-AC

[MN Renovator]

"But it still does not account for where you came up with the wacky statements about the weather?
I'd really like to know..."
If this is directed at me, I just explained in my previous post that this was information based on the statement of the OP and my response was based on the graphs you provided in post 15. If this wasn't directed at me, carry on.

[AC_Hacker]

OK, now I get it... when you said:

Originally Posted by MN Renovator

It only gets down to 45 degrees in west washington.

You actually meant, "...the statistically average temperature for the coldest months in western washington is around 40F but variations in weather can cause spikes above and below that amount by 23F degrees (the generally assumed designed temperature for this weather shed is 17F) or more, so it is advisable to plan your heating accordingly."

Sorry, I didn't read between the lines...

-AC