I looked up what kind of radiators I have and found that they're called "heating convectors." It isn't feasible to wrap the metal fins in a blanket. At best I could cut foam insulation board to sit on top of the fins and duct tape the same to the underside.
Advice on mini-splits
- Thread starter Wear More Layers
- Start date
-
Active since 1995, Hearth.com is THE place on the internet for free information and advice about wood stoves, pellet stoves and other energy saving equipment.
We strive to provide opinions, articles, discussions and history related to Hearth Products and in a more general sense, energy issues.
We promote the EFFICIENT, RESPONSIBLE, CLEAN and SAFE use of all fuels, whether renewable or fossil.
- Status
I looked up what kind of radiators I have and found that they're called "heating convectors." It isn't feasible to wrap the metal fins in a blanket. At best I could cut foam insulation board to sit on top of the fins and duct tape the same to the underside.
Assuming Mitsubishi does honor warranties for online purchases, the closest in size is the MSZ-GE18NA. I'd get 3,600 more BTUs (at 47F) than with the Fujitsu, but also a drop in HSPF from 12 to 10 and COP from 3.91 to 3.33. The Mitsubishi is $250 more. So which one pays for itself faster? The one that offsets slightly more of my oil heat or the one that is more efficient?
With my elec rate, I would go for the more BTUs, with your elec rate, I would go with the higher COP. The financial 'risk' on payback is that oil price drops 30% (small chance could happen) and then you don't run the mini.
On the radiators, pics of yours or similar on 'net?
On the radiators, pics of yours or similar on 'net?
See http://inspectapedia.com/heat/Heat_Convector173-DFes.jpg for an image of the metal fins around copper pipes. The exterior looks like http://inspectapedia.com/heat/Heat_Convector126-DFs.jpg .
If you wanted a permanent solution, and there were really no valves, I was suggesting having something like this made:
![[Hearth.com] Advice on mini-splits](/talk/proxy.php?image=http%3A%2F%2Fwww.westchesterwoodcrafters.com%2Fimages%2FDSCN2698a.jpg&hash=fdce8ba98c233f5a503851bea892dc9e "[Hearth.com] Advice on mini-splits")
to go over, and put some foam between the radiator and the cover, perhaps with a small cutout.
Edit: sorry I am stupid. You can just wrap the fin assembly (as in your first picture) with alum foil and then put the cover back on. Wrap half the length, cut BTU output by 50%, 3/4s, cut it by 75%, etc. Cheap and easy. If it gets too cold, take some foil off.
to go over, and put some foam between the radiator and the cover, perhaps with a small cutout.
Edit: sorry I am stupid. You can just wrap the fin assembly (as in your first picture) with alum foil and then put the cover back on. Wrap half the length, cut BTU output by 50%, 3/4s, cut it by 75%, etc. Cheap and easy. If it gets too cold, take some foil off.
Last edited:
Just laying a cloth on top the fins would accomplish a great deal. You would stop 90% of the heat xfer. No need to "wrap" it with anything. It s the air flowing thru the fins you are trying to stop. THere is no need to insulate.
Note: There is a preview function before you post messages (select other options, then preview). This allows you to see e.g. if your photos are upside down or not, or how any graphics will display in the final message.
Exactly, you're preventing the radiator from cooling off and having to make the boiler run more to compensate for the heat given off. The hot water then just flows into the next room without giving up any heat in the room where it was covered.
Exactly, you're preventing the radiator from cooling off and having to make the boiler run more to compensate for the heat given off. The hot water then just flows into the next room without giving up any heat in the room where it was covered.
Not saying you're wrong but looking at the photo of the convector cover, that type usually will have shut off controls for each room with a pipe below the floor running into the next room. I would double check particularly if you can see in the basement how they run -- if there isn't a pipe running below the floor into the next room (in fact, the shut off's might even be down in the basement, though they are typically under the convector cover in the room).
If not then all you want to do to prevent the heat transfer to the room is to put something above or below the fins (or both--though on top is easiest) preventing air flow from rising through the fins.
If not then all you want to do to prevent the heat transfer to the room is to put something above or below the fins (or both--though on top is easiest) preventing air flow from rising through the fins.
I'm feeling kinda dumb because I can't find any shut-off valves. I have bleeder valves to get air out of an individual unit, but that's it. I think each radiator runs a complete loop from the basement because when I get air in a line and that room goes cold, the other rooms still get heat. I have a total of 9 radiators, with 20 pipes feeding off the main loop in the basement, again leading me to believe that each radiator has its own circuit. (Why there are 20 pipes and not 18 is a mystery. I'm missing something somewhere.)
Anyway, aluminum foil, a rag, or foam board should decrease heat to a room.
Anyway, aluminum foil, a rag, or foam board should decrease heat to a room.
If you actually do have separate lines to each convector then it should be relatively easy to install a valve in one (or more) of them to shut it off -- to more elegantly control it than by placing a barrier over the fins. And those valves can be thermostatic (more costly of course than non-thermostatic valves) but allowing a room to have it's own thermostat.
Putting one thermostatic control valve in one convector would be relatively simple (not really effecting the rest of the system the way a zone valve system would usually be).
But if you do actually have a home run system like that, I would be surprised if there isn't already some means of disabling a separate run to a room, though there might only be balancing type valves (control it with a slotted screwdriver--vertical position is off, parallel to pipe run position is full on)
Putting one thermostatic control valve in one convector would be relatively simple (not really effecting the rest of the system the way a zone valve system would usually be).
But if you do actually have a home run system like that, I would be surprised if there isn't already some means of disabling a separate run to a room, though there might only be balancing type valves (control it with a slotted screwdriver--vertical position is off, parallel to pipe run position is full on)
Last edited:
Hi Wear More Layers,
The RLS2H is the lower temperature (equivalent to Mitsubishi Hyper-heat) unit. I did all of the COP research myself, and though I can't find the documents now on my computer, the links Floydian sent seem very familiar. You should be able to find a similar document for the RLS2H detailing the COP. From memory, the COP of the RLS2 and RLS2H are the same to a certain temperature and then the COP of the RLS2H is better at lower temperatures. Basically, with the RLS2H you get better (and actual useful) performance below 5 degrees F.
In regards to why the HSPF of the RLS2H is worse than the RLS2, I asked the installer this same question. He had no idea. When researching HSPF, I came to the conclusion that the lower temperature units are penalized somehow since they operate over a broader temperature range, and naturally have a lower COP at lower temperatures since they still operate at those lower temperatures. So I ignored the HSPF as a pretty "useless" figure of merit for anybody really trying to understand what unit to get. Go with the COP and the operating temperature range. Maybe there are some others here who can shed more light on this...
I have the 15RLS2H, and I can tell you that it cranks out a lot of heat, even at low temperatures. I'm satisfied with every bit of it except a typically Japanese difficult user interface (especially in regards to setting up a timer schedule). Realistically, you will likely get a bad user interface on any unit you buy, so I wouldn't let this get in the way of choosing the Fujitsu.
How much do you think you spend per year in electricity? What's the elec rate in your part of NY? I did a little research and learned that CT plans to increase fees on electric bills, and electric rates themselves are going to go up, too. Yay CT.
The rates vary throughout the year. In winter, all-in, it is probably about 12 cents/kWh, and in summer 15 cents/kWh, not including monthly fees. I know that CT has run way higher recently. Once I get through this first winter, my solar array will be able to earn enough credits over the summer to power the heat pump for the winter while the house is unoccupied and in the (long) process of renovation. In December, for instance, we had ~1200 degree days, and my consumption was ~800 kWh with the heat pump set at 60 degrees (constant). I burned a little oil on the coldest days (maybe about 40 gallons). The house does need insulation, and it is pretty leaky right now. Lots of work to do.
If you ran the heat pump just during the warmest part of the day (e.g. daylight hours), your COP would be better and cost/BTU less. I think you will find that the winter cents/kWh rate is likely lower in the winter than the summer. Be sure to ask if you are trying to justify payback on the system for heating use.
If you ran the heat pump just during the warmest part of the day (e.g. daylight hours), your COP would be better and cost/BTU less. I think you will find that the winter cents/kWh rate is likely lower in the winter than the summer. Be sure to ask if you are trying to justify payback on the system for heating use.
12 cents/kWh!! That's just crazy. I checked, and my rates don't go down in the winter. There's every indication that electric rates in CT will only go higher, and one HVAC guy I know thinks I'm crazy for adopting a heat source that relies on elec.
Without going too far off topic, what are the advantages for you to have a wood stove, heat pump, and oil heat all in one home?
Just to be clear - there are two houses that I write about, the one I live in today (wood stove, oil boiler with cast iron radiators) and the one I am going to be renovating (oil furnace, mini-split heat pump) and that is currently unoccupied. There is also a wood stove in the basement of the to be renovated house, but it is a slammer install and I wouldn’t consider running the wood stove it unless there was a seriously long power outage.
The advantage in the house to be renovated is that the mini-split is set to run at 60 degrees and the oil furnace at 50 degrees. If it gets too cold for the mini-split to cover the heat load, the oil furnace kicks in as a backup. This oil furnace is old, and I am trying to minimize wear on it since I don’t want it to need expensive repairs before I replace it with a (likely) wood boiler.
A recent observation from cold weather mini split operation is the output varies with outdoor RH. If it is damp and snowing the units goes into defrost mode far more often than cold and dry for the same out door air temp. My unit is covered so the snow is not physically getting on it but RH really makes a difference.
Last edited:
outdoor RH is def a factor. When it is >35 and raining, the outdoor coil is kept warmer than 35 and dry by the latent load, and you get more/warmer output. Drop a couple degrees, and suddenly you are doing long defrosts during wet/snowy weather, and losing 20% or output. (on a conventional split HP)
That was something that impressed me about the specs for the Hyperheat units. The defrost cycle is limited to only a few minutes per hour iirc.
But the way different mfrs handle defrost is an important consideration. Was to me anyway when I was looking at regular split systems. Eg. Goodman had one of the least sophisticated defrost cycles, controlled only by time -- i.e. would go into defrost regardless of whether it needed it or not. Other mfrs have more sophisticated mechanisms eg. checking temperature of the coils to see if there is frost build up or not.
But the way different mfrs handle defrost is an important consideration. Was to me anyway when I was looking at regular split systems. Eg. Goodman had one of the least sophisticated defrost cycles, controlled only by time -- i.e. would go into defrost regardless of whether it needed it or not. Other mfrs have more sophisticated mechanisms eg. checking temperature of the coils to see if there is frost build up or not.
An update on cold weather mini split usage, I have been running my one ton mitsubishi hyper heat pretty much continuously since November 10th with it set at 65 to 68 degrees. I have only shut it down on nights when the expected temp was predicted to go below -5 degrees. As of today the unit has used 954 kWh for an average usage of 14 kWh per day. Generally when the temps are over 20 degrees day time with some sun I can heat the entire house. Its a small home 952 sq ft on the main floor and 408 sq feet on the second floor office. As long as it is above zero at night and above 10 during the day it seems to be able to keep the main floor at temp but there is definitely some temp difference between rooms and my office loses out. I have been eating up net metered solar power to date so I still haven't bought any power and expect I can run another month before I run out of net metered credit. One of my solar arrays is on my roof and it was entirely offline due to snow cover for about half the period. It also only went on line in June so I didn't have a full sunny season to build up extra credit.
I have been running the wood boiler during the cold dark stretches mostly to supply heat to the office and heat domestic hot water.I have not run it for the past week but expect it will get fired up as the temps drop. I originally used the heat pump less aggressively and went through a cord and half of wood since fall. My wood usage has slowed down with more aggressively use of the heat pump. I am definitely still in the learning curve mode. I think once I have a chance to see how much surplus electric power I can generate between spring and next season, I may elect to run the heat pump when the outside temp is over 20 degrees to take advantage of the better COP and output at higher temps and use more wood.
I have been running the wood boiler during the cold dark stretches mostly to supply heat to the office and heat domestic hot water.I have not run it for the past week but expect it will get fired up as the temps drop. I originally used the heat pump less aggressively and went through a cord and half of wood since fall. My wood usage has slowed down with more aggressively use of the heat pump. I am definitely still in the learning curve mode. I think once I have a chance to see how much surplus electric power I can generate between spring and next season, I may elect to run the heat pump when the outside temp is over 20 degrees to take advantage of the better COP and output at higher temps and use more wood.
One ton as in 12000 btu? How is then noise level when the house is up to temp?
One ton is the nominal rating of the unit. One ton is 12000 Btus/hr . In reality the heat output varies with more heat as the temp rises and less as the temp drops.
The noise level is variable, if I am heating the second floor office I have to run the fan at high to throw the heat over to a stair well and its noticeable (about what you would get in hotel room). If I am heating just the main floor I can run the fan at the middle speed. I drop it down to low at night and the house is warm in the AM. The most annoying noise is when the unit goes into defrost as it has a variety of fan noise as it does its stuff. Today its snowing out so its defrosting more often. Given the forecast for the next few week I will be running the boiler more often.
The noise level is variable, if I am heating the second floor office I have to run the fan at high to throw the heat over to a stair well and its noticeable (about what you would get in hotel room). If I am heating just the main floor I can run the fan at the middle speed. I drop it down to low at night and the house is warm in the AM. The most annoying noise is when the unit goes into defrost as it has a variety of fan noise as it does its stuff. Today its snowing out so its defrosting more often. Given the forecast for the next few week I will be running the boiler more often.
Interesting. So you hear that inside the house when it goes into defrost. Wondering how often and how long it's doing that. Have understood there's no electric backup with these hyper heats, and they don't blow cold air during defrost, so it's just that you get no heat and there's an annoying noise in the defrost cycle.
Interesting. So you hear that inside the house when it goes into defrost.- I live in a very quiet location in the woods, there really isn't a sound from the defrost as much as there is a variation in fan noise, it just cycles through a range of fan speeds from off to on. I expect those who play music in the background or are not sitting right near it wouldn't notice. I located mine to optimize heating and that meant that the indoor unit ended up right near my Lazyboy chair. If I had located elsewhere I would notice it less.
Wondering how often and how long it's doing that. - Happens more often as the temp drops and the amount of the humidity in the air. On a sunny day in at 20 F, its very rare, add in snow or fog and it happens more often. In snow and fog I have turned it off around 10 degrees. No matter what as it drops down to zero, it starts to happen frequently.
Have understood there's no electric backup with these hyper heats, and they don't blow cold air during defrost, so it's just that you get no heat and there's an annoying noise in the defrost cycle. You are correct that there I no electric backup. There can be draft during the defrost cycle as the unit does run the fan at a higher speed. With regards to noise I discussed it above
Wondering how often and how long it's doing that. - Happens more often as the temp drops and the amount of the humidity in the air. On a sunny day in at 20 F, its very rare, add in snow or fog and it happens more often. In snow and fog I have turned it off around 10 degrees. No matter what as it drops down to zero, it starts to happen frequently.
Have understood there's no electric backup with these hyper heats, and they don't blow cold air during defrost, so it's just that you get no heat and there's an annoying noise in the defrost cycle. You are correct that there I no electric backup. There can be draft during the defrost cycle as the unit does run the fan at a higher speed. With regards to noise I discussed it above
An update on my mini split. The various cold stretches have made an impact, I figured by now I would have 35 degree days and 20 degree nights (so do the maple sugar folks) but it has been getting down to zero or below. The mini split is cranking along. I am up to 1600 kw since Nov 11th 2013. I expect my net metering credit will be gone this month. I have cut my wood usage for my boiler which given the colder winters is good. I have pretty good sun exposure during the day so once the sun is up and the blinds are open, the heat pump usually goes idle by about 10:30 AM and stays that way until 4:30 PM.
- Status
Similar threads
