Author Topic: Heat Pump HVAC Maintenance?  (Read 4612 times)

EngiNerd

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Heat Pump HVAC Maintenance?
« on: June 06, 2015, 04:26:28 PM »
I bought a home with a Maytag Heat Pump unit (Q6SD-X30K) and I have lived here for a couple years now and just ran out of filters.  I was looking into whether to buy more disposable filters vs lifetime electrostatic filter (at first thought seems more economical and environmentally friendly however some say it decreases efficiency leads to higher electric usage) and I realized I have a lot to learn about heat pump units.  For instance some coil maintenance and back washing of the unit can help bring down heating and cooling costs.  The previous homeowner said every couple of years I should have appliance guy perform maintenance on it.  So I figured a knowledgeable Mustachian could set me straight pretty quick.

Permanent or Disposable Air Filters?
Easy enough for a novice to take the cover off to clean the coils and back wash?
Any other maintenance that warrants calling a professional?

Thanks!

EngiNerd

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Re: Heat Pump HVAC Maintenance?
« Reply #1 on: June 08, 2015, 07:10:37 PM »
I take it as a bad sign that there are no Mustachians with knowledge/experience on heat pump units to offer input...  Are they over priced or otherwise a poor choice for heating and cooling?

Sid Hoffman

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Re: Heat Pump HVAC Maintenance?
« Reply #2 on: June 08, 2015, 08:15:43 PM »
I guess your post just didn't get traction the first time around.  You generally see heat pumps in the southern states where it rarely goes below 20F, which is often cited at the point below which a heat pump gets you no gain in efficiency versus straight inductive heat in the winter.  However, in the climate zones where heat pumps make sense, I know from shopping for homes that it seems you almost exclusively see heat pumps anywhere that doesn't have natural gas for heat.  They're simply the most cost effective way to do both central heating & cooling in places where temperatures say between 20F and 120F with the sweet spot zones in the 40-100F range as the most common temps.

I've had both disposable filters as well as several years using a lifetime filter.  I really didn't like the lifetime filter because they said all you have to do is hose it out, but that was never enough to get everything out of the one I had.  I still ended up having to hit it with 120psi compressed air from my home air compressor every few months.  Sure enough, even after hosing it for 5+ minutes, blasting it with high pressure air would get another visible cloud of debris blowing out of the filter.  I'm back to using disposables again since that's the only way I know for 100% sure that the filter is perfectly clean.

Any heating/cooling system is extremely expensive to repair and even more expensive to replace if it fails early due to poor maintenance.  For that reason, I probably spent half of the last 15 years with service contracts.  Then for something like $250/year, they'd come out in the spring & fall to clean the indoor & outdoor coils (split unit) and check the performance and refrigerant levels.  Yes, it's an added expense but with replacement at $7000 or more, it could mean the difference between getting 7-10 years out of a unit or getting 15+ years, at least here.  It's so hot out in the desert that they pretty much never last much longer than that before something fails or corrodes to the point of requiring replacement.

So starting from the start: what climate zone are you in, and how many square feet are you intending to do?  Are you looking at zone heating & cooling, or central whole-home?

EngiNerd

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Re: Heat Pump HVAC Maintenance?
« Reply #3 on: June 08, 2015, 08:39:14 PM »
I live in Central AR so it is fairly rare for the temp to get below 20F.  My house is about 1100 SF and really the unit does pretty good, in the winter it can be a little cool for my fiance, or some visitors remark on how cool it is but it fits my needs fine.  I prefer no to have too drastic of a difference between the indoors and outdoors anyways.  But it does run often in the hottest months and the winter months so I figured any maintenance I can perform, or have performed that makes it more efficient would be worth it.  Is it pretty much a consensus that a service contract (with the manufacturer?) is the best value for maintaining HVAC systems? 

Thanks for the info on the air filters!

Sid Hoffman

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Re: Heat Pump HVAC Maintenance?
« Reply #4 on: June 08, 2015, 09:10:07 PM »
Is it pretty much a consensus that a service contract (with the manufacturer?) is the best value for maintaining HVAC systems?

Do you have a split unit?  If it's a split unit with the compressor and condenser coil on the ground and the air handler / evaporator in the ceiling, then you can certainly clean the outdoor one yourself.  The manufacturers generally say just to hose it down with a regular garden hose and no pressure-building attachments while the unit is off so as to not cause shock-cooling to the coils.  I used to do that myself.

As for the indoor portion of a split unit, it was actually a little scary getting up in the ceiling crawlspace of both of my last two homes, so I was genuinely worried I'd become an injury statistic if I tried to maintain that portion myself.  Same applies for rooftop mounted ones: slip-fall is the second most common cause of accidental death in America right behind automobiles, and slipping off your roof while cleaning a rooftop A/C unit is not how I want to go.  I'll let you make that call for yourself though.  I'm admittedly more cautious than most.

Dan_at_Home

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Re: Heat Pump HVAC Maintenance?
« Reply #5 on: June 09, 2015, 06:20:30 PM »

Heat Pump Unit
================
I have a heat pump but for the most part do not touch for a couple reasons.  (1) The system uses the highest amount of amps of anything in our household, those it could be deadly if you forget to first turn the power off. (2) The freon like substance that it uses is hazardous to handle, the tubes are pressurized, and you need a license to even handle it and (3) To service it would require specialize skills and literature that I do not process.  Instead, I pay a company to look at every year or two.   

In fact, the heat pump is probably the only part of my household that I don't mess with.  I have been thinking about this for a while, and if you want to be more mustachian, the best route is probably to leave the heat pump alone and install a secondary, simpler, and easier to understand heating system such as wood stove.  With these, you can service it yourself, it is simple to understand, and cheaper to operate assuming you can find a free supply of fuel.  In the worst cold winters, use the wood stove instead of the heat pump to heat your house.

Filters
=============
In regards to filters, I use the cheap fiberglass MERV 4 disposable filters.  Like you said, I also did research and the higher rated MERV filters, i.e the permanent ones, actually block too much air from getting to the unit and result in higher electricity costs and lose of efficiency.  These fancy filters claim to last "up to 3 months" but in practically, in my house they last only 1 month.  The higher MERV filters also claim to purify the air, however, these filters and the heat pump were never design to purify air in the house.  If you want purified air buy a portable air purifier for the room you spend the most time in.  Thus, I found it better to use the MERV 4 disposable filters to maximize air flow to the heat pump while still filtering enough for the heat pump to function. 

One thing I do that I am not sure if it is 100% ok or legit, is that I will actually take a high powered vacuum cleaner hose over my cheap MERV fiberglass filter that is dirty to clean it.  Even though this is probably not recommend by the manufacturer, it works surprising well on the low MERV filters and they look pretty clean afterward.  Usually, I will do this once a month to the filter when the heat pump is in use.  After each vacuuming I will mark a star on it.  After 5 cleanings or stars on it, I will dispose of it.  Lowes and many of the hardware stores stopped selling the fiberglass MERV 4 filters so that customers would be steered to buy the ultra expensive fancy pants ones that cost $15 a piece.  However, you can buy a large box of the cheap fiberglass MERV 4 filters from amazon, and it is a great deal.


 


Sid Hoffman

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Re: Heat Pump HVAC Maintenance?
« Reply #6 on: June 09, 2015, 06:35:30 PM »
In fact, the heat pump is probably the only part of my household that I don't mess with.  I have been thinking about this for a while, and if you want to be more mustachian, the best route is probably to leave the heat pump alone and install a secondary, simpler, and easier to understand heating system such as wood stove.  With these, you can service it yourself, it is simple to understand, and cheaper to operate assuming you can find a free supply of fuel.  In the worst cold winters, use the wood stove instead of the heat pump to heat your house.

I wouldn't personally recommend this since it's horrible for the environment and air quality.  Burning wood is actually banned in a lot of places for significant parts of the year because the effect on air quality is so damaging.  It's cheap in dollars, yes, but that cost is simply transferred to the health of the environment you live in.  There's a ton of resources about it on the internet, and some heart-breaking articles on the very real effects it has on children.

Bob W

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Re: Heat Pump HVAC Maintenance?
« Reply #7 on: June 09, 2015, 06:51:05 PM »
+1 on clean the filters and reuse.

I have never vacuumed but I'll try it.   I uses the hose, soap and water and sun dry.   I don't mark them.

In the future I will down grade my MERV 13 to a MERV 4 to see if there is a difference.   I never have dust on the furniture.   My filters are huge at 29 by 31 and I have to special order. 

I've heard about the drag on the system theory and not sure I buy it.   With an 8 sq ft opening that is fed by a 3 sq ft return line I think I'm safe?   

I do run my blower 24 seven due to 3 levels in house.

My system is a ground based system.

It is very efficient and averages $140 per  month year round for all my household electric (all elec house) on a 3000 sq ft house.  (9cent kw).    For comparison our bill was 85 with no AC usage in May.  So yeah about 60 bucks a month heat and cool.

The 20 degree deal doesn't apply to my ground based system and I have no resistor back up. 

It is also worth noting that you shouldn't turn on your "emergency" or "back up" heat until you are below zero.   Your unit will work fine till around zero,  it just won't be as efficient.    Running your resistors between 0 and 20 can cost big bucks. 

I used to build homes and put heat pumps on them all.  The owners were impressed as hell with their low utility bills.   I mean very impressed.   One guy had a February bill of $85 in the house I built and his home for sale was $140 at 50 degrees for gas heat. 

Bottom line --- heat pumps rock. 

kimmarg

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Re: Heat Pump HVAC Maintenance?
« Reply #8 on: June 09, 2015, 07:46:01 PM »
I guess your post just didn't get traction the first time around.  You generally see heat pumps in the southern states where it rarely goes below 20F, which is often cited at the point below which a heat pump gets you no gain in efficiency versus straight inductive heat in the winter.   

This is outdated info. Newer heat pumps work down to -20F and remain more efficient than straight electric baseboards well. Below zero. Mine was chugging away this winter at -17F and decreased my propane useage 40% (I gave baseboard hot water on propane in addition to the heat pump)

That said the guy who installed mine said to just take out the inside filter and wash it once a year. I might have a different kind though. Mitsubishi 15,000 BTU hyper heat model....
« Last Edit: June 09, 2015, 07:49:52 PM by kimmarg »

churchill

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Re: Heat Pump HVAC Maintenance?
« Reply #9 on: June 10, 2015, 09:17:07 AM »
The electrostatic filters can fail, so you might be better off with the disposable or washable kind. You're best off getting it professionally inspected seasonally by a local company, then only need to clean the outdoor coil when they recommend it. Sometimes a hose will work, other times it may need a harsher chemical. Make sure there aren't a lot of bushes around the unit. The guy with the Mitsubishi has a different type of heat pump (split), and the one Bob W is referring to a geothermal heat pump, which yours isn't. To warn you that Maytag you have is a builder grade unit (manufactuered by Nordyne) so it's probably not going to give you the longevity all homeowners hope for.

Sid Hoffman

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Re: Heat Pump HVAC Maintenance?
« Reply #10 on: June 10, 2015, 11:06:31 AM »
This is outdated info. Newer heat pumps work down to -20F and ...

...

I might have a different kind though. Mitsubishi 15,000 BTU hyper heat model....

A heat pump alone is not going to be effective in -20F.  Based on what you stated, you have a combo unit, where you have a heat pump but it also has a 15kw heat strip to provide heat when the temperature drops below a certain threshold.  At that point it's not really fair to say you're using your heat pump for heat, as you are really getting heat from a 15kw inductive heating element.

Here's an example of info from a HVAC company:

Quote
Equipment varies and so does the operating range. However, 40 degrees is a general standard where some heat pumps begin to lose efficiency. Most will continue to work down to 17 degrees, with some equipment going below that. When the thermostat (via outdoor temperature sensor) senses the outdoor temperature is too cold for the heat pump to be used as the primary heat source, it automatically switches to a secondary heating source (gas, propane, oil or electric).

That last part, where it says "or electric" is where your 15kw induction strip kicks in.  It's a perfectly fine way to do things, as it costs a little more to buy a heat pump with the additional heat strips, but ultimately it should still save you power as it will only switch to inductive heating when it is cold enough to justify it.  In same cases, that means only at night, and during the daytime when it warms up it runs as a conventional heat pump still.  You also sometimes see it referred to as "boost" heat from manufacturers, especially when they are referring to the smaller 5kw strips.  I also see it referred to as emergency heat in some docs.

So you were right that you can buy a heat pump even in a very cold area, although with the asterisk that it needs to have something to fail back on (such as a heat strip) when the temperature drops below the effective range for that given heat pump and its ratings.

kimmarg

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Re: Heat Pump HVAC Maintenance?
« Reply #11 on: June 10, 2015, 07:25:15 PM »
This is outdated info. Newer heat pumps work down to -20F and ...

...

I might have a different kind though. Mitsubishi 15,000 BTU hyper heat model....

A heat pump alone is not going to be effective in -20F.  Based on what you stated, you have a combo unit, where you have a heat pump but it also has a 15kw heat strip to provide heat when the temperature drops below a certain threshold.  At that point it's not really fair to say you're using your heat pump for heat, as you are really getting heat from a 15kw inductive heating element.

Here's an example of info from a HVAC company:

Quote
Equipment varies and so does the operating range. However, 40 degrees is a general standard where some heat pumps begin to lose efficiency. Most will continue to work down to 17 degrees, with some equipment going below that. When the thermostat (via outdoor temperature sensor) senses the outdoor temperature is too cold for the heat pump to be used as the primary heat source, it automatically switches to a secondary heating source (gas, propane, oil or electric).

That last part, where it says "or electric" is where your 15kw induction strip kicks in.  It's a perfectly fine way to do things, as it costs a little more to buy a heat pump with the additional heat strips, but ultimately it should still save you power as it will only switch to inductive heating when it is cold enough to justify it.  In same cases, that means only at night, and during the daytime when it warms up it runs as a conventional heat pump still.  You also sometimes see it referred to as "boost" heat from manufacturers, especially when they are referring to the smaller 5kw strips.  I also see it referred to as emergency heat in some docs.

So you were right that you can buy a heat pump even in a very cold area, although with the asterisk that it needs to have something to fail back on (such as a heat strip) when the temperature drops below the effective range for that given heat pump and its ratings.

Ok, so you're right that the heat pump is not my only heat at -20F - I also have propane hot water baseboard. It is possible to heat your whole house with heat pumps at cold temps (my coworker does it) I just didn't have the cash to install a large enough system to take my whole heating load (this one does about 40%). 

So also yes, " When the thermostat (via outdoor temperature sensor) senses the outdoor temperature is too cold for the heat pump to be used as the primary heat source, it automatically switches to a secondary heating source" for my model this happens at -20F. Since my lowest temp this winter was -17F it never shut off.

No, I don't have an induction strip. That would be just like an electric baseboard and much less efficient . I have this model :
http://www.mitsubishipro.com/en/professional/products/heat-pump-systems/m--p-single-zone/m-series-heat-pump-systems/msz-fhmuz-fh

EDIT to add: ok that link says it only works to -13F, I thought it was -20F and I swear it was on at -17F this winter. Let's just say "below 10 below". Saved me over $1000 this past winter!
« Last Edit: June 10, 2015, 07:29:49 PM by kimmarg »

nobodyspecial

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Re: Heat Pump HVAC Maintenance?
« Reply #12 on: June 10, 2015, 10:46:21 PM »
No gas here and electricity is expensive once you go over a baseline amount.
Pacific northwest so no need for AC and outside temperature is only rarely below freezing.
I was considering an air source heatpump (on rock so a ground coil is tricky) - mainly because the furnace is noisy and I have pets so want the option to run a fan+filter without heat.

Does it make (financial) sense if you only need heating?

kimmarg

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Re: Heat Pump HVAC Maintenance?
« Reply #13 on: June 11, 2015, 03:16:04 AM »
No gas here and electricity is expensive once you go over a baseline amount.
Pacific northwest so no need for AC and outside temperature is only rarely below freezing.
I was considering an air source heatpump (on rock so a ground coil is tricky) - mainly because the furnace is noisy and I have pets so want the option to run a fan+filter without heat.

Does it make (financial) sense if you only need heating?

It does for me, but run your own numbers. I'm in northern New England. No natural gas. Electricity is around 15 cents/ kWh, $2.79/ gallon for propane (similar for heating oil). I cut 500 gallons of propane with it and only increase my electricity by a couple hundred. Around $1000 savings this year. We also run 7000 Heating Degree Days per year. I didn't install it for AC although I suspect we may turn it on for a few of the hottest days.