Replacing Natural gas Steam heat with Hyper heat Mitsubishi split system

paddys · January 28

Hi,

We met with a salesman yesterday and received a quote for replacing our natural gas heat with a Mitsubishi hyper heat 5 unit split system.

In 2015, we also installed a 5 unit Mitsubishi split system, which does not do a good job of heating when temps go below 30 degrees. So, we have been using the split system only in Summer for cooling. We use natural gas heat with 4 big radiators in our main floor.

Drawback of our current split system: It doesn't do a good job of stopping when target temps are reached. The thermostats in our current split units were never good.

Drawback of our current natural gas steam heat. The heat has a hard time coming out of the 2 radiators in our bedrooms which are farther away from the boiler. May be because the vents are at the top as opposed to the middle as recommended by Dan Holohan in his book.

We live in Queens, NYC. Our home has one main floor with 4 split units and a basement which has the 5th split unit. About 1000 sq. feet in the main floor and 500 square feet in the basement. The 4 units are one each in 2 bedrooms, one unit in living room and one unit in kitchen cum dining.

Our steam heat makes my skin feel very dry when it is really cold outside.

Now the salesman has suggested a hyper heat Mitsubishi split system which will work well up to minus 10 degrees. Thus we can get rid of the natural gas Steam boiler and the 4 big radiators and get $8,000 rebate from Con-Edison, our electricity supplier.

What are the things I should be considering to check whether this is a good idea. Any suggestions for adding some humidity?

Thank you in advance for your comments.

Paddy

Jamie Hall · January 28

First, humidity. Dry winter air is a consequence of warming cold air — and the heat source doesn't matter. So… to increase the humidity you will have to use a humidifier. They range from whole house units, if you have ducted heat, to individual room type units. There is no other way to increase the humidity.

Now on the heat. You mention, or at least imply, that you are not really as comfortable with your current heat pump heat, but that the steam heat is comfortable. A different brand or type of heat pump is not going to be any more comfortable, though it probably won't be much less, either. So I'd have to ask… why even consider switching? Doesn't make sense to me.

STEAM DOCTOR · January 28

You can get cheap humidifiers, for a few bucks

Mad Dog_2 · January 28

Paddy...Stay with the Steam and get a Local Queens Steam Pro like The Steam Doctor to look it over. 2nd, we dont discuss pricing here. Please edit that out. Thanks and let us know how you make out. Mad Dog

ethicalpaul · January 28

you can try the new heat pump and take advantage of the incentives, but there’s no reason to yank out the steam system right away. (Unless the incentives mandate it)

You might be glad you didn’t after trying out the new heat pump for a winter.

I’m very pro new tech but it’s difficult to pull heat out of 10F air like you are experiencing this morning, for example.

Ask the sales person what fuel they use in their house or if they have ANY employee’s house with these that you can visit this week

pecmsg · January 28

Do NOT get rid of the steam heat. Keep it as a backup for WHEN something fails.

I stopped installing any minis above dual zone. WHEN something goes wrong the entire system is down for days.

The dry air is from a leaky house!

paddys · January 28

https://forum.heatinghelp.com/discussion/comment/1884708#Comment_1884708

Hi Mad Dog_2, I edited the price out. Thank you for your feedback.

Mad Dog_2 · January 28

U bet...Think about what's in YOUR best interest, not the salesman. Mad Dog

STEAM DOCTOR · January 28

The old timers, used to hang some sort of a basin, off of the radiator or a radiator cover. They would fill that with water. As the heat came on, the water would evaporate into the air and provide some relief.

STEAM DOCTOR · January 28

But seriously, if dry air is your concern, you can go to CVS and get humidifiers for 25 bucks or something like that. Did this for years when my kids were little, to help with the constant ear infections....

STEAM DOCTOR · January 28

I am not what happened with those blank posts. But it's an important lesson. Sometimes it's best not to say anything at all!!

Steamhead · January 28

https://forum.heatinghelp.com/discussion/comment/1884728#Comment_1884728

I think you can delete them, or @Erin Holohan Haskell can.

Jamie Hall · January 28

Jittery finger, @STEAM DOCTOR ! Done it myself.

The basin on a radiator trick works marvelously well — for steam heat. It doesn't work well, though, unless the radiator is really hit. We use it all the time.

HeatingHelp.com · January 28

https://forum.heatinghelp.com/discussion/comment/1884744#Comment_1884744

I deleted them. Thanks!

winnie · January 28

Get your steam system fixed. Good steam is nice.

Get external thermostats for your minisplits. Most minisplits have to continuously run the fan to know what the room temperature is, and so when you don't need heat you still have the fan on.

Suitably designed minisplits can certainly provide heat at -5F or even lower. But they get less efficient as it gets colder. I've personally tried my minisplits at -6 and they made heat.

The heat from the minisplits comes from blowing tepid air (not hot air), so you end up have to run at a higher room temperature for the same comfort.

I personally find the radiant heat from my steam system more comfortable than the blowing air heat from my minisplits. But both work to heat my house.

I typically use my minisplits down to about 30F, and then switch to oil fired steam. My cutover is based on cost of operation, but on days when the outdoor temperature drops I sometimes don't notice that it's gotten cold and I should switch to steam. If I just want to heat one room I'll use the minisplit down to 20F and not bother to heat the whole house.

pecmsg · January 28

if you purchase a Hyper Heat system then by all means use it. If you want steam heat then do not go with hyper heat.

Ironman · January 28

Does your house have masonry walls? If so, you’ll never feel warm using any type of forced air - especially a heat pump.

Any type of forced air heats the structure by heating the air. That’s exactly backwards of how it should be done. Radiators heat the mass of the structure which in turn heats the air.

An old house with masonry walls acts like a big heat sink drawing heat from the air. You can have 75* air and the walls will still be 55*, making the structure uncomfortable. Radiators will warm the walls from heat rays which will then warm the air.

Keep your radiators and send the salesman packing. Newer does not mean better.

winnie · 3:01PM

Just to add to my previous comment:

When I say that the radiators are more comfortable, what I mean is that if I am positioned near to a heat source, it is much more comfortable to be a couple of feet away from the radiator than a couple of feat away from the minisplit indoor unit.

I have the floor console type of indoor unit, not the typical near ceiling type, so I probably notice the blowing air more. When I am away from a heat source (say in the hallway in the middle of the house), both feel exactly the same.

Another factor with the minisplits designed for heating at low ambient temperatures: they often have small resistance heaters in the outdoor unit to melt condensate and to keep the compressor case warm. Only about 50W of draw, but this is a continuous parasitic load. I personally find that the optimal use of minisplits is for 'shoulder season' heating, and that 50W draw when it is cold outside is pure loss.

Based on my experience in Western MA with oil fired steam heat and minisplits, I'd recommend that you keep your existing minisplits until their natural end of life. You have a working system for air conditioning and shoulder season heating, so there is no reason to pay for that again.

As I said already, get your steam heat fixed.

Then use both in a hybrid fashion; use the minisplits when you just want to take a bit of chill out of the air, and the steam heat when it is cold.

When the time comes to replace the minisplits, the technology will probably be better. At that point get the units that can provide heat on the coldest days. Then you will have the option of picking whichever is cheaper to run.

Replacing Natural gas Steam heat with Hyper heat Mitsubishi split system

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