¶ Heat Pump Water Heaters and Ducting
Yo , yo , yo . How's it going , andy ? What's up ? Ha ha ha . Bonus episode Bonus episode . We recently talked about heat pump water heaters and we got some messages on them over on in the DMs on Instagram . So it just says reminder anybody . If you want to get in touch with us , you can look in your like , for instance in your Apple or Spotify podcast app .
There's right in the description of the show . There's little links right directly to our DM over on Instagram , but you can hit us up over on Instagram . I'm at at Mechanical Hub . Andy is at mck m-i-c-k , underscore plumb p-l-u-m-b , and you can send us any kind of message or feedback or anything about the show . Start that out with um m-t-g-a , m-t-g-a .
There you go . Thank you , boy .
I tell you I'm here for you , I'm here for you .
I appreciate it . You're here for me , so anyway , back to it . So we talked about heat pumps recently . We got some messages about it and it got brought up in conversations between you and I about ducting these things out , and so let's get into that . We don't usually talk about like install work or technical stuff on the job .
It's not really been the theme of the podcast , but let's go that direction for this one a little bit . Yeah , I have . I'm just going to make a statement to start it out .
Yep .
So I live in a cold climate . The our water heaters are not sitting outside , they're . You know , we have basements for um on on kind of the normal year , we're six to seven months heating season . Right , consider that , I mean , that's , that's significant , right there , right , um , and we see a lot of gas , tons and tons of gas .
Like the majority of appliances and homes in my area are gas and they have been up , will be for a long time . Right , Um , that the gas doesn't come into this venting but the the whole idea of a heat pump does .
So you have to have a minimum cubic foot capacity of the space that they're in in order for these things to operate properly , right , right , I mean , I think most people listening are going to understand that , right , yeah , yeah , exactly .
I think , I think the the place where people get into trouble is when they , you know , come in and they're like oh , we've got this 50 electric or 65 gallon electric and it's in this closet at the end of the hall . Yeah , you know , on the two story , you know , and you're you're like , oh , okay , yeah , that's great , you know .
So you walk in there and right smack in the middle of the house is this closet that it's got a 65 gallon water heater in .
Well , I see I don't see those a ton . I see I guess it's not . They're not unheard of , right ? They're not in our like standard . You know like four , eight plex kind of town home buildings , you know what I mean . Even under those we see a lot of atmospheric gas water heaters . Yeah , believe it or not , in a closet of course , like you're saying .
Yep , plenty of electric in those situations too . Smaller , going to probably be 50 gallon . Yeah , and I say smaller because we see a lot of very large electric storage water heaters when it comes to electric . We see them 80 , 110 , 105 , stuff like that .
Yeah .
Because we have , like those off peak programs with a heat at night at a discount . Yeah , okay . So my statement , I didn't make it , it's my opinion , and this is based off of where I work and a couple of different things , some experience .
I think these things have to be ducted to the outside because they have these exhaust ducts so that the cold air that they're putting out . I personally believe that they should be ducted to the outside . That's my opinion . Right , I'm going to stick by , unless you can convince me otherwise .
I would agree , in most common residential applications , you're going to want that , You're not going to want that thing in the , in the , or taking room air , cooling it and returning , basically , cooler room air it .
In some cases that we , as we talked about in the in the last episode , where we talked about heat pump water heaters , you end up with areas that are just too cold , yeah , oh , especially in the winter . Uh , if you , if you don't have , you know , a good source of heat there , then then you're going to have that .
The only place that I've , I have one heat pump water heater in a commercial application . Yeah , and it works phenomenally well on the basis that it's in an elevator room . There's a mechanical room with an elevator machine in it .
That's and there's 80 degrees and that heat pump , water heaters just in there live in life , you know , and it cools the room a little bit . It doesn't even party put a dent in it . But if you had an application like that , if you had a big , big , um you know , hydronic heat manifold or man or mechanical , room or something like that .
Yeah , I mean , it sure makes sense .
But yeah , I get that . Well , I'm . I'm thinking , though , like you said , uh , the standard residential application , maybe I'm , maybe I'm not ducting it or even considering ducting it if it's a big unfinished basement and I don't see that thing getting finished anytime soon .
I'm not talking about like a modern new house that just doesn't have a finished basement yet . I'm looking at it Like the one I was in just the last couple of weeks ago with that that big uh CU three a job , yeah , Um , you know , 120 , 100 year old , 100 plus year old farmhouse , Right Basement is not getting finished . Promise you that .
It's seven feet .
I mean the ceilings are six and six foot eight or something like that , right , yeah , yeah , uh , we're not finishing that . It's a little leaky , it's probably it's a little cooler in the summertime down there already , because it's got like a stone and block foundation , that soft block stuff , yeah , and then it certainly isn't sealed up , you know .
So there's some , some infiltration there , right ? Maybe you don't duct it there . Maybe there's a benefit too . Maybe the people are like well , heck , I'm going to sleep down here when it's 95 degrees outside because it's so nice and cool . I just got to listen to it and try , and you know , right , right .
Yeah , you know we've . I think the majority of them that we're looking at , that we've looked at . In the last year I've absolutely said we're going to duck this out . Here's the duct kit . I'm including it in the price . Um , we're going to route the the duct work out . You know we can pull room air , but we still have to have your makeup air .
I think you were talking about it before we started recording your snorkel kit , um , or your snorkel intake , um . You're going to have to have some sort of makeup air if you duck the thing out . Well , unless the house is leaking , Sorry go ahead . I was just saying , unless the house is leaky old windows , something like that .
But Well , you can't rely on that .
I mean we , we are required to an obligation to account for makeup air when we put in , like , a range hood . Yeah , um , when we put in exhaust fans , that has to be considered . You know we have to consider makeup air . Yeah , so , because you don't want to pull a negative on the house , you know .
So , even in these old , leaky houses , um , we can't take into account , well , this house leaks , nobody's doing a manometer test on this old house and be like well , there's enough makeup air just through all the windows , no blower doors happening just to put in a fart fan . It's not theory at all , it's just by practice and by cold dictation .
We do have to consider makeup air If we're exhausting on these water heaters . I would imagine that we have to consider that just the same , right ? Yeah , I mean , it's literally just an exhaust fan , it's not , or I guess ? Yeah , I mean at that point adding a fan , it's part of the water heater , but yeah , yeah , so it shouldn't be another permit item .
But yeah , I mean , I think that if you haven't done a heat pump , water heater where it's ducted something that you got to keep in mind , you know , at least on the , the Aero Therm on the Bradford White , you've got to order the duct kit for it , right , so it's not a big deal and I don't even think it's that expensive , but it's like a hood that connects
on the outlet and then there's also a hood to connect the inlet . And the last one that we did that , I feel like , works fairly well we pulled air out of a unfinished basement and we discharged air either back into the same unfinished basement or we discharged air into the kitchen area which was directly above it . So house has an AC or it doesn't .
Didn't have AC at the time and we thought , well , let's just let it push that cool air up into the , into the kitchen area .
So you just got like a floor register in and put a boot in there , or what ?
We actually had access to put in . I don't remember what we did , like a 10 inch oval , like a 10 by four oval that came up in the wall and then we had a wall boot made for it and it's all low velocity , I don't remember what it is 175 CFM or something like that . 150 CFM . It's pretty low , low volume , but it's you got .
The thing to remember is you have to connect it with eight inch , so it's eight inch round duct , it's not not a small no , no , and they , they recommend not doing it in flex .
No , you should be rigid , yeah , and you know , and ideally , that discharge line , if you're going to be using it and you're going to be running it with a really cool inlet temperature , you know , if you're , let's say , you're down in the fifties and you wouldn't be a bad idea if it's going to be somewhere where condensation is going to be an issue , as far
as you know , property damage , it would be a good idea to insulate that too .
The exhaust , exhaust duct or exhaust duct in it's going to it'll discharge that air , I think , I think , I think most likely , yeah , it'll discharge down to 38 degrees , I think is the low , low , the temp point where it cuts off there , shuts down the heat pump and says , hey , you know what we're not , we're not really doing a making a big impact here .
Well , indoors , that I mean if you've got cooling happening , that indoor that dew point should be higher , should be at that or lower already I'm guessing .
But if you got a relative humidity let's say like 45% , so yeah , so I mean that's kind of in the middle , yeah , but if I could see it condensing for sure , like you just said in your example and again I acknowledge what you said is , you know , if you didn't have air conditioning , this is something you're definitely going to want to consider .
Yeah , yeah , I mean you're , you're dry mountain air there . You guys don't really have any , I mean reliably don't have humidity . No , that's a stupid way to say that . It's pretty typical your humid , your humidity levels are considerably lower than , let's say , ours here in the Midwest .
Yeah , absolutely , I mean your homes is probably pretty darn low even without cooling , and that's a moving target here . I would caution anybody that's not doing any cooling to just leave that duct run wild in a situation where you're not you know , where you don't have a cooler environment that is running , put it that way , I mean it's probably going to sweat .
Yeah , yeah , and I don't think you're going to have an issue If you're . If you're just not ducting it , let's say you're sticking it in that big unfinished basement in the old , you know old stone foundation home that's got water infiltration and moisture issues already . Yeah , it's not going to be a problem if you don't duct it .
No , no , Because the unit has a condensate drain built into it . It's going to capture anything that it produces . But if you have a cold duct discharging off of it , then you're going to have an issue .
¶ Heat Pump Water Heaters and Humidity
You know , in our case here I mean our humidity fluctuates a lot from day to night and that's where a lot of our condensation issues if we're going to have them happen .
In that twilight sunsets , humidity jumps up quite a bit as it's as the sun's setting , Because we'll get down in the low teens for outdoor humidity relative humidity , I mean in the summertime , which is kind of crazy .
We're more humid than that in the winter .
Yeah , and then you know we'll be in the 60s or 60 , 70% humidity throughout the evening and you'll get lots of dew , lots of condensation , you know , and then as soon as it's 100 degrees again , it's down in the teens or I don't know . It's been a long time since I've heard single digits of for humidity .
When we get it stuff , that's when stuff is breaking , like you can hear trees drying up and things like that . It is kind of wild .
It's crazy , it's so different here . Like it's so different we have . I'm looking at my phone right now , so take it for what it's worth . Here's your midwestern weather forecast . Yeah , here's your central Minnesota forecast . It's a little callback . Today the average humidity is 52% . The dew point is 61 to 65 .
So , and like it is just straight up , like that's normal . Yeah , that's just super normal . It's not high or anything . We get some pretty nasty levels of humidity and dew point . Like we see dew points up in the upper 60s and , yeah , you know , mid to upper 70s . That's when , like no thanks , yeah , yeah , it's pretty crazy .
Actually , it's pretty gross and it gets worse the further south you go . Like it's not , I mean it's , it is pretty extreme here in Minnesota , believe it or not , for that humidity , but yeah , so like it's just my opinion Because of those heating months here in Minnesota .
This is , like I said earlier , strictly based off of my experience , and I'm basing this off of feedback from customers .
They don't love the idea of this thing , like really cooling down the space , and if we're in heating mode , I get a lot of calls , a lot of blowback Like why would I want my furnace running or my boiler running to heat my water heater and it's like well , I mean , you're not wasting energy .
You know your boiler isn't necessarily running more because you have a heat pump water heater . That's not really how this works , but I can see why people would think immediately that you know one is a direct cause of the other . I don't think that we're adding to the load .
I think you're definitely benefiting from whatever heat that you're creating , regardless of you know whether it's more than you need or not . I don't , I don't know , I just don't want to deal with it .
Right , right , no , and I hear that too , and I guess the way I've kind of combated that is talking with a homeowner and saying , hey , listen , okay , so you know , yes , it's going to cool the room . No , you're probably not going to see it on your gas bill when your furnace is running , because it's not to that extent .
You know , if you remember back from our last conversation , if we're talking about using room air to heat our water through mechanical advantage in our heat pump , we're talking about 4000 BTUs an hour . Yeah , that's right . I mean , your 96% efficient furnace is , or 80% efficient furnace is not going to notice 4000 BTUs an hour . That's , that's a .
That's a an irrelevant number in terms of that . If we're talking 40,000 , then okay , yeah , we got something to , we got something to consider . Do we need to up size your furnace , you know ? At that point then I'm questioning well , you know , what do we really do in here ? Why are we doing a heat pump , water heater ?
I think we got the wrong , wrong end goal in mind here , right .
I agree ,
¶ Tips for Ducting and Duct Work
so I agree . Well , there you go , ducted or not ducted , totally up to you . I'm ducting them . If I can , I am too .
I here's , here's . Here's one . Just a small tip . Look at the instructions . There's this piece of paper it's usually like folded in half , like maybe eight and a half by 11 . It's like it's kind of like a knee pad . Yeah , it looks like a knee pad or a good shim , yep , it's .
It's semi absorbent so you could use it to swap up some water if you got a little leaker . But open that thing up about midway through . They're going to talk about ducting and duct work , sizing and how many fittings you can use and the maximum length . You can't run this thing up through the attic and out through the roof .
Probably not going to work out if you got to go clear across the basement with it either . Anyway , yeah , that's my tip of the day .
They're just not made for that , not yet . All right , dude , that was a good one . Yeah , it was . We are awesome . I just love it when we're so good . Yeah , don't break your arm there . Pat yourself on the back . See you , dude , all right .