Suggestions for Heating an Attic.

MikeinNEPA

So I plan to finish off my walk up attic for my son to use as a bedroom/ play room sometime over the next year and I'm wondering how I would be best to heat it, The home is a 1925 Victorian and the Attic will likely be around 500-600 Sqft when finished with a mix of very high( 12') and fairly low (6.5') ceilings. I plan to have the roof insulated and vented, but I'd like to see what the best options are for this type of space for both heating and cooling.

The home now has hot water heat through radiators but the lay our of things would make running plumbing from the basement to the attic difficult, I do have a NG line on the second floor that is unused and could easily be run to the attic ( black iron.) Electric is something I'd also like to avoid if possible as we have municipal run electric and its rather expensive.

Thanks in advance for the suggestions.

Jamie Hall

Hmm... I think I'd go with a minisplit for both some air conditioning and for heating at least in the shoulder seasons. If you have NG or can get it up there easily, how about a vented gas stove/fireplace for additional heat when needed and some interesting decorative effect as well?

MikeinNEPA

any recommendations on the split unit?

Solid_Fuel_Man

Fujitsu, Mistubishi. Both work well.

Zman

What climate are you in?

MikeinNEPA

Northern Penn.

EBEBRATT-Ed

First thing first is a accurate heat loss and heat gain. How can you decide what to install without an accurate load?

I agree with the mini split. Electric baseboard to supplement.

I wouldn't use gas up their

Gordy

I agree with comments above. I would think for the square footage, the feasibility of infrastructure, and the need to cover two types of conditioning loads. Mini split would be the way to go.

I wouldn't do a vented gas stove for constant conditioning of a sleeping space. That's just me.

newagedawn

sounds like a 18,000 btu vented gas space heater should do the job, but a heat load would be more accurate, but in summer the attic will get real hot so mini split would be a great idea, ive had great success with mitsubishi, they cost alittle more but are reliable if installed properly and they have a great troubleshooting staff

HVACNUT

> @MikeinNEPA said:

Electric is something I'd also like to avoid if possible as we have municipal run electric and its rather expensive.

>> obviously you will need an electric source for any option.
What Is the usable length of the space? If you put a ductless head on one end wall, will it throw enough heat/cool to satisfy the other end?
With a 12' high ceiling, you could opt for a high efficiency heat pump ducted split system with electric coil backup. A/H in (new) attic. Leave significant room for service of the equipment.

MikeinNEPA

MikeinNEPA

This is the area I have to work with, There will be electrical service up there (already is,) but I'd like to avoid using things like electric base board for heat.

What is the thought of using a vented wall heater or vented ng stove in the 18k btu range along with a simple ceiling fan in that tall center area?

Also I've never dealt with split units before, I know one section goes inside the home, does they other have to be on the ground or can it be mounted to the exterior?

Big Ed_4

The outside unit can be mounted on the exterior wall with an wall bracket . The power from the breaker box goes to the outside unit . Between the outside/inside unit refrigerant and control lines are run , thy make line set covers to make it look nice ... Even if you can find an route for the lines to the ground for the condenser , raise if off the ground above the normal snow line .. If unit lies in the snow and ice, using the heat pump eats away on the outside coil ...

Ask me how I know that

MikeinNEPA

Big Ed I think I have a pretty good idea how you know that LOL,

So as long as the unit can be mounted on a 2nd story exterior well that will work out well, how far can the outside unit be from the inside typically?

Also does the inside unit need to be installed on a vertically level service or can it be installed on on of the slopped ceiling sections?

Big Ed_4

You can mount the condensor up on an second story if you like . There is an min length of of line set by the manufacture . I seen 12'-15' call for..... It can be coiled up if too close but only on an horizontal only . Something about if line set too short the the higher velocity of oil rushing back can damage the compressor . Horizontal coiling to remove any oil traps .. I know Guys .. Just stating the book if you need in the future to call tech support or any warranty issues ..

No ...none of the indoor units can be on an sloop . It's critical to be level which these units .. Thy make an ceiling cassette you can box up in the ceiling or an hidden model that you can hide behind a wall or up in an ceiling .. and they also make an floor model . you can mount on the gabled wall ...

You will need to oversize the unit if using the heat pump for heat .. And I would throw in an electric strip for back up .. They make models that capture heat -15* now...

Note , you stated you have a gas line the floor below .. A Question.. Is that line the proper size to handle the extra load ? Most of those old gas lines where undersize in todays code. Your plumber can tell you..

Bob Bona_4

I wouldn't be too thrilled about servicing a heat pump perched off a bracket 2 stories up. Get it on the ground with a stand or pump risers. No electric strips in the inverter heat pumps, the ultra low ambient ones have a heated pan in the exterior unit for enhanced defrost.

Paul48

No wet-wall and stack run through that space?

Big Ed_4

Heat strip for back up meaning Electric baseboard , You may need just in them cold winter nights ..

MikeinNEPA

Big Ed said:

You can mount the condensor up on an second story if you like . There is an min length of of line set by the manufacture . I seen 12'-15' call for..... It can be coiled up if too close but only on an horizontal only . Something about if line set too short the the higher velocity of oil rushing back can damage the compressor . Horizontal coiling to remove any oil traps .. I know Guys .. Just stating the book if you need in the future to call tech support or any warranty issues ..

No ...none of the indoor units can be on an sloop . It's critical to be level which these units .. Thy make an ceiling cassette you can box up in the ceiling or an hidden model that you can hide behind a wall or up in an ceiling .. and they also make an floor model . you can mount on the gabled wall ...

You will need to oversize the unit if using the heat pump for heat .. And I would throw in an electric strip for back up .. They make models that capture heat -15* now...

Note , you stated you have a gas line the floor below .. A Question.. Is that line the proper size to handle the extra load ? Most of those old gas lines where undersize in todays code. Your plumber can tell you..

Its a 1/2" line that is split off a 3/4" line coming off the main, on the 3/4" line there is also a 30K and 18k ventless that I use to warm up my garage and 3 season room.

Nothing else is off the 1/2 besides a Dryer which will be getting moved before this project begins.

Paul48 said:

No wet-wall and stack run through that space?

Not sure what that means lol.

Bob Bona said:

I wouldn't be too thrilled about servicing a heat pump perched off a bracket 2 stories up. Get it on the ground with a stand or pump risers. No electric strips in the inverter heat pumps, the ultra low ambient ones have a heated pan in the exterior unit for enhanced defrost.

How far away can the exterior unit be away from the interior part? I've never dealt with these and I'm not sure if its something I'll try my self or have it installed, but either way I'd like a good understanding of what can and cannot be done.

Also are these generally 115v or 230v in the sub 20k btu range and does power run to the heat pump then to the interior unit?

Big Ed_4

You can install them as close as you like, as long the line set is the manufactures min length ... It depends on the model you install . There is also an max lengh ...

I only seen the small 9k-12k run off 110V , The line goes to the condenser which powers the inside unit ..

Can you install it your self , in theory and law no one is allowed to sell you refrigerant unless you are certified to hand it . Refrigerant comes with the unit .Anyone can take the test and then you have the internet , Buying on line is a problem for it usually voids the warranty and tech support . You need tech support to diagnose any future problems .

Once hooked one need to charge the system with 400# of nitrogen to check for leaks .Then purge the system with nitrogen .. Once tight with no leaks , system need to be brought down under vacuum to and bellow 500 microns to evacuate moisture out ... Moisture will turn to acid and freeze if left in.. Then the condenser service ports can be opened .. I don't know can you do it?

To answer for Paul , He was looking for an way down though the house . The wet wall is the space in the where all the bathrooms waste lines and water is run , the highest pipe is the vent going though the roof though the attic .. Normaly the space runs straight up .. We look for them to run pips and wires ..

To size an gas line you take the attire load and use the furthest appliance in lenght for sizing the main line coming in up till the first branch . Then calculate the same for the next run after the branch . Each riser , the pipe running off the main to the appliance min 3/4" should be sized for the length and size of appliance .. Meter size should be same or more then the total load in BTU's .. If over you will need an bigger meter ..

MikeinNEPA

BigEd, Thanks so much for the info, I like to tackle whatever projects I can, but it seems in this case that its more cost in tools and training than I would save in labor doing that my self.

As for the gas line, I'll have to measure the load over all, but I'm curious as a ball park, Is a modern gas dryer a lot more, less or similar in gas needs to a 18K btu vented heater?

Also I really appreciate your level of detail, I really like to understand everything even if I won't be the one installing it.

As for a wet wall, there are 2 though only one would be even remotely accessible, the gas line runs some what through one of them. If I could get a run of 100-150ft run between components of the a/c I actually do have a very good place to run it with out needing to put it on the gabled roof, and running the lines internal to the house.

ChrisJ

Unless I'm mistaken, in the US the EPA does not require any certification to purchase R410A at this time.

I believe that will be changing 1/1/18 though.

My biggest concern would be buying equipment online due to the lack of warranty, regardless of what the websites claim.

Paul48

@MikeinNEPA
Thanks Ed......Sorry I didn't get back sooner. I was looking for an easy way to the existing system. You won't need much heat in that space if you seal the space. I'd use 2lb urethane foam. It's so dense, you don't have to vent the rafter bays. If you want to heat it....light a candle

Jack

For straight heating i would suggest a Rinnai EX17C. Modulates on the house fan and the burner from 8,200-16,700 btu. 2.5" hole for direct vent system which comes with the unit. Built in progammable stat, quiet and cool to the touch. I would locate it under the window. The clearance from the vent to a window/door is 9".

MikeinNEPA

Paul48 said:

@MikeinNEPA
Thanks Ed......Sorry I didn't get back sooner. I was looking for an easy way to the existing system. You won't need much heat in that space if you seal the space. I'd use 2lb urethane foam. It's so dense, you don't have to vent the rafter bays. If you want to heat it....light a candle

I was thinking that, with the closed cell foam, I'm getting differing info on applying it directly to the room boards, the installers of the stuff tell me its not needed but it could void the warranty of some roofs. The roof I have is standard asphalt shingles now and I don't know if that is or is not under warranty, but in the next few years I'm considering one of those Tesla solar shingle roofs ( note my comment on being in an area with high electrical costs.)

I don't know what their deal is with venting or not venting, but I don't want to get cornered if I don't have to, given the relative low cost of installing that corrugated venting, is there any drawback to venting it even if not needed?

ChrisJ

MikeinNEPA said:

Paul48 said:

@MikeinNEPA
Thanks Ed......Sorry I didn't get back sooner. I was looking for an easy way to the existing system. You won't need much heat in that space if you seal the space. I'd use 2lb urethane foam. It's so dense, you don't have to vent the rafter bays. If you want to heat it....light a candle

I was thinking that, with the closed cell foam, I'm getting differing info on applying it directly to the room boards, the installers of the stuff tell me its not needed but it could void the warranty of some roofs. The roof I have is standard asphalt shingles now and I don't know if that is or is not under warranty, but in the next few years I'm considering one of those Tesla solar shingle roofs ( note my comment on being in an area with high electrical costs.)

I don't know what their deal is with venting or not venting, but I don't want to get cornered if I don't have to, given the relative low cost of installing that corrugated venting, is there any drawback to venting it even if not needed?

I completely do not know, but my guess would be Tesla, along with other panels don't care if it's vented or not. The panels should be absorbing the energy rather than your roof. The roof will likely stay much cooler under the panels.

Do the Tesla "shingles" go directly on plywood, or do they get placed on top of standard shingles?

Gordy

Most shingle warranties are as good as the paper they are printed on. Prorated materials no labor for tear off, and installation. Find any info from the shingle manufacturer on exceptable roof deck, and or attic temps temps let me know. However poor venting, or non existent venting of the roof will void your warranty, and certainly a crutch they will use if issues arise.

Never understood that. The face of the shingle will most certainly be hotter than the back side in any case. Venting from my perspective is more of a moisture control application for unconditioned attics.

Gordy

Also be aware that photovoltaic cells degrad over time. I'm not sold on solar PV yet.

ChrisJ

Gordy said:

Also be aware that photovoltaic cells degrad over time. I'm not sold on solar PV yet.

I highly doubt they would let you install it over your apartment anyway.

Paul48

@Gordy makes a point.......In 15 years, will those shingles be available? Racks on top of a standing seam roof can be adapted to whatever is the flavor of the day, without sacrificing the water-proof aspect of the roof. Modern metals used in standing seam roofs will last 75 years and stand up to hurricane winds.

Gordy

What ever you choose to call a dwelling @ChrisJ. It is no longer a problem of mine

Gordy

My point about PV is their inherent inefficiency to begin with. Couple this with the more real estate they require, and their loss of efficiency over time. 20% efficient to 10% in 10 years, or less. makes one rethink that avenue. Using them as a roofing platform is smart as a dual purpose role provide you have the solar exposure, and enough roof to obtain your energy needs.

Gordy

I would do solar DHW before PV. Slam some pex with plates between the rafters to the roof deck, and utilize some of that solar gain in the attic for DHW. Isolate with an HX using glycol in that zone, and roof melt in the winter becomes a tool off the boiler.

Paul48

They should be doing so much more with concentrated solar. You can make DHW, or store it for heating, while you run a Stirling generator and make electricity. Because it makes it's own electricity, it can be made to track the sun, unattended. The "Talking Heads", just talk the talk, they don't walk the walk.

MikeinNEPA

As far as the Tesla Solar Shingles go, they come with a lifetime warranty, given its a new product how well they honor it is another question, though they seem fairly big on the whole do the right thing.

Now over all it sounds like it would be better to vent the roof with those corrugated plastic sheets between the 2x6's since it won't hurt and it's one less thing to have to worry about in a warranty issue down the line.


I can't say enough how much help I get from this forum every one is really great.

Gordy

Interesting they have the shingles broken down into 3 different warranties.
Lifetime on the glass portion.
30 on weatherization (leaks)
30 on power output.

I would like to see the fine print before committing. I'm sure there is an exceptable degradation over that period of time.

I will say it's a nice looking product, and seems durable.

ChrisJ

From what I've seen the Tesla roof's website is very vague about a lot of things. In general, I don't like vague. It makes me suspicious.

Honestly, very disappointed considering what I expect from them.