Leaning towards heat pump

Jamie Hall

https://forum.heatinghelp.com/discussion/comment/1808344#Comment_1808344

All that you mention comes under the heading of serious abuse, which I mentioned.

Also, I wouldn't say I was biased towards any particular heating system. My bias, if any — as is true of my "day job" — is to find the best solution possible to the particular problem at hand for the particular people at hand. It could be any possible heating system, in the context of heat.

And no, Cedric is hardly my only responsibility. I am a monk, responsible for a parish of several hundred folks, as well as all other maintenance on a large and rather creaky estate. I am also well into my eighties, if that's worth anything.

Brad White

Pluses and Minuses, if I may-

Firstly- gut reno with air sealing, insulation, all good things. I wouldn't bother with any heating system changes until I declared victory with my building enclosure. Insulation is energy you pay for once and can reduce your system size day-one.

Air-Source Heat Pumps (thinking Mitsubishi Hyper-Heat/M-Series but of that genre):
Pluses:
1. You get AC if you've never had it before.
2. The heat is gentle and great on a day when the first fall chill comes in, but you do not want to heat the entire house.
3. They are remarkably quiet.
4. Properly-sized, they will serve down to a design day, meaning zero to single-digits with a COP of about 1.7, but in the many more warmer hours (20F to 40F), your COPs are 4-plus, even 5.0.

Keep the steam as a back-up though. Or HW. If you are going all-in, you have options, but if all-electric, and you have power outages, you are pretty much out of options. Any system that a portable generator can run, will do. Heat pumps alone are a commitment.

Minuses:

1. Aesthetics. The wall-hung units do not impress me for residential use. I prefer ducted or console units. Maybe cassettes but those are a bit commercial for my take. Stay with ducted and change your filters regularly.

2. Lack of Humidity control in cooling mode.

Understand that unless you have a positive dehumidification mode, not just an "ignore cooling set point because it is sticky" mode, your ability to dehumidify is incidental by chance. Understand that the way these save money, is to track temperature- if the space temperature is reached and the unit was delivering 54F air, the supply temperature is released to float upward, tracking space temperature and cooling again as the deviation from set point widens.

If you cool without removing humidity, it positively will increase your RH. Yes, these systems do have condensate lift devices, drains, etc. and yes, you must dispose of this condensate, but it occurs incidentally to the cooling process.

My $0.02

EBEBRATT-Ed

I am not a big proponent of forced air systems. But if you want AC or a heat pump what are you going to do?

The problem with an air system is that 99% of the residential jobs have undersized duct work and choked returns and inadequate supply distribution that causes noise and drafts.

My old boss was a real PE in two states and graduated from the Coast Guard Academy and passed the tests to get his licenses. He ran the oil Co I worked at when I was fresh out of school. He knew how to design a duct system. He didn't design a lot of duct systems as he was too busy running the company but I saw enough of the ones he did design and they worked very well.

You have to compare apples to apples and oranges to oranges. You can't compare a crappy forced air system to a good hot water or steam system or vice versa.

Face it, probably 80% of the country is forced air. Hot water and steam is a small market whether we like it or not.

LRCCBJ

https://forum.heatinghelp.com/discussion/comment/1808346#Comment_1808346

Low water, clogged returns, clogged pigtails, failed pressuretrols, failed vents, and contaminated water simply does not constitute "serious abuse". These are maintenance items that typically befall a steam system over time…………something a FHW system does not suffer. You could lose a pump…………or a zone valve………very rarely but that's about it. They work silently and without any attention by the "staff"…………with a part time position (largely irrelevant).

Hot_water_fan

Americans like AC. In some online echo chambers steam and hot water reign, but let’s be realistic: heating = forced air for the vast majority. You need to sell people on the hydronic up charge and that hasn’t been going very well to date.

Steamhead

https://forum.heatinghelp.com/discussion/comment/1808362#Comment_1808362

Well, let's see- expansion tank issues, water leaks, air binding……………………

No heating system is maintenance-free.

pedmec

We are out of Boston and I can tell now that the company i work for is installing the mitshubishi hyperheat everywhere in the northeast. I personally have done a little but because i am not in the plan and spec department i don't do much with it. my work is mostly wet work. But in conversations with the installers and service techs we have had no problems. Two of the owners kids have installed them in their property and said said they have not had any cold complaints. i ask around. ill get it straight from the guys that work on it everyday.

Teemok

The idea that you strip a house to its bones and do major efficiency upgrades and then close it all up without committing to using the existing radiators or removing them completely due to committing to a future with gas furnace backup isn't smart. Use them or remove them at the time of remodel.

Can anyone give some good reasons why not to convert a steam radiator system to FHW? The old pipes would be used as a common return and new home runs to manifolds with barrier pex as supplies. Obviously the existing radiators must be oversized for the load. 1920, I bet they are. Seems a shame to go FA with vintage cast iron mass already in place. Is it really all steam or just rip them out because a furnace is cheapest? Is the idea to just leave them in place and not use them? The thermal stability of constant circulation and the mix of well placed combo radiant and convection emitters isn't desirable?

My own FHW radiant system is 23years old, has never once failed and i've done zero to it. I mean nothing.

Steamhead

@Teemok , this has been discussed ad nauseum on this site.

Some objections are:

1- hot water rads only give off roughly 2/3 the output of similarly sized steam ones;

2- hot-water runs at over 10 times the pressure of steam, so any weak points in pipes or rads WILL leak;

3- steam return piping is often too small to carry the load when running HW;

and on and on. Learn steam rather than trying to convert it.

Teemok

1 - It's either a go or no go, by case. Big deal. After renovations the loads can be much lower than the reduced by a 1/3 output. If the CI was originally oversized by huge %, like much of it was, than I don't see this as a real issue. Paint them an emitting dark tone and take the convection limit covers off.

2 - Weak points. Ok, test and fix. I've seen and read about many successful conversions. Not sure if this is a paper tiger or not. Maybe that's correct and some crappy old piping should be removed when doing a to the bones renovation. I'm betting the radiators do just fine with sub 30lbs.

3- Piping is too small to carry the dramatically reduced loads? Single pipe system piping would be too small? Maybe that's true sometimes but that's why it's investigated first. Obliviously, sometimes it works well because it was commonly done.

I learn about steam for the pleasure of knowledge. There's not much functional steam around my parts. I love to work on it when I find it and enjoy being able to. There's lots of big money around here that likes the benefits of hot water. My childhood Phllly three story home had a converted steam radiator system. Likely done decades before I was born. Don't remember leaks being a big thing.

If those are the top negatives, seems a weak position. I'm fine with, I like steam systems and don't like seeing them converted. Honest and makes sense.

Jamie Hall

Folks, I've said it before but it looks like I'll have to say it again:

There is no one right answer.

Every application, every job, is different. Determine and use the right equipment for the specific application and client and install it right. If you don't know how, direct the client to someone who does.

Steamhead

https://forum.heatinghelp.com/discussion/comment/1808393#Comment_1808393

Do you want to be the guy who promises great things from a conversion and then the project goes south? I sure don't.

Since you haven't looked at previous threads, here is one:

https://forum.heatinghelp.com/discussion/145002/actual-savings-over-steam-heating

TL-DR version: someone came on here and bragged about a steam-to-water conversion where the fuel consumption was reduced by a third. He found out the hard way that others have done this by fixing the steam, for a LOT less money and risk.

ChrisJ

I'm pretty sold on it being a fact that converting any system is never going to save anyone 33%.

I could see gaining 10% best case, but never 30+.

Teemok

Risk is a great reason. I'll do some reading. 33% is a lot to expect or claim. I would guest 8-10% on burner and hx and then some % from the operational gains of ODR and modulation. Maybe 14-15% but for a real problem steam system and very good FHW it might be more gains. If efficiency is the only conversion benefit, you have to be burning lots of fuel to make 14% pay off. There are a list of other factors that might make a conversion a good idea. Failed masonry flue, boiler space savings, tech availability, zoning….

No right answers and case by case sounds correct. Blanket statements and investigation dismissal isn't. If the investigator lacks critical thinking skills, the risk of failure is much higher and the potential for improvement with steam is less likely.

What would you guess the efficiency and comfort loss is of having a steam boiler that's above 200+% of peak load?

Installing gas, electric, flue, condensate drain and protection for two furnaces is easier than using the existing installed boiler location and connections? Open loop HW coil might be a good backup heat option if ripping out the old CI is the path.

Steamhead

@Teemok said:

"What would you guess the efficiency and comfort loss is of having a steam boiler that's above 200+% of peak load?"

Probably similar to a hot-water boiler or scorched-air furnasty or heat pump that is oversized that much.

Teemok

@Steamhead said: "Probably similar to a hot-water boiler or scorched-air furnasty or heat pump that is oversized that much."

A quick DOE read gives a 7% figure for over sized loss. They give an industrial example. That sounds high for a residential application but the physics are universal. A wild guess 4-5%? The discomfort factor is hard to quantify.

If I'm looking at a project that has a working steam system and the owner is remodeling down to studs seeking efficiency and the results of keeping the steam working as designed will result in a condition that will be less comfortable and have a 4% (oversized loss) plus a 14% (burner and operational loss) compared to a great FHW system, I'd be a fool to not at least look at options to save 18% and have a more comfortable non short cycling system that more techs can fix. Saving from zoning would be more depending on the case. If the use pattern is 10 days a year, logic says, incur the losses, cycle wear and tear and be slightly less comfortable for 10 days.

I understand that many here feel that any real world efficiency gains are not worth the efforts and resulting MODCON maintenance. I can understand that position, especially if their MODCON experiences have been bad.

I know more than a few well meaning smart enough people have invested in chasing fantasy gains and ended up doing it wrong, realizing no gains and getting more maintenance costs and shorter boiler life. That fact doesn't mean it can't be done well.

If the use pattern is 7 months a year @250kBTU/hr, an 18% savings is a carrot worth chasing.

Thanks for your explanations.

Jamie Hall

The standby loss on a boiler has almost nothing to do with whether the water in it is eventually turned to steam — or left as hot water.

I might add that the "lost" heat sometimes regarded with horror for a steam boiler as it is coming up to steam or a cold start hot water boiler, or the "lost" heat on a hot water boiler held warm for DHW, is NOT lost heat, unless the boiler is in a separate, isolated building.

A very common — and remarkably misleading — problem in looking at systems (and for some reason heating systems seem to be particularly prone to this) is failure to look at the entire system, and instead cherry-picking one part or another and basing conclusions on that single part.

Sometimes this is problematic only for a single system, such as a residence. Other times — and to keep politics out I won't cite even obvious examples — the resulting errors are used to drive large scale policy mistakes.

Toasted

https://forum.heatinghelp.com/discussion/comment/1808376#Comment_1808376

Would be great to hear more about the experience installing the HH systems and what to look out for when doing so. My approach will be fully ducted, not the mini-splits or cassettes. I would think the cooling is fairly straightforward, and have heard that in the northeast there's no issue as it heats deep into the minus double digits.

Teemok

What I got from that thread posted above by Steamhead should not be shared here.😁 or maybe anywhere…. Peaks through the blinds. I had no idea how deeply personal a physics debate can be. I know the horse vs automobile analogy is not the same as this FHW vs steam thing but I bet there were a few horse guys in the peak of horse decline that would have loved to give a combustion engine engineer the alley spa treatment. That doesn't make the engineer wrong or the horse guys bad. It's all very understandable. To be clear this thread is in A/C, HP and Refr. I will be more careful with my suggestions in future. I'm just here to continue learning and maybe help some. With all due respect to the steam folk, I'm backing away slowly, smiling real friendly like.

Toasted

https://forum.heatinghelp.com/discussion/comment/1808459#Comment_1808459

This thread definitely took on a life of its own, although I do appreciate everyone's contributions. That said, I do not quite follow all the technical aspects of it as I am a layman.

I do find your thoughts intriguing as I was contemplating whether it made sense to use the existing steam furnace and convert to water and run them through the radiators, but as others have mentioned, that could come along with issues,

My original reason for avoiding FHA was due to what I knew about furnace-based systems, e.g., super dry air, etc., but have recently learned that the newer heat pumps (such as Mitsubishi Hyper Heat) do a decent job maintaining comfort while being able to heat in colder than usual conditions compared to the old heat pumps.

ChrisJ

https://forum.heatinghelp.com/discussion/comment/1808497#Comment_1808497

For what it's worth dry air isn't caused by forced hot air, it's caused by bringing outside air in via drafts. Forced air systems, especially if designed wrong tend to exaggerate those drafts.

My dad's 2006 house tends to run RH in the 30s without any humidifier and he has forced hot air and that's in northern PA. My 1860s drafty house gets very crispy, easily into the teens without a humidifier and I have steam heat.

Pulling outside air in and warming it causes dry air nothing else. If you're insulating and sealing things up I wouldn't be concerned about this regardless of your choice.

Teemok

My last post was intended as humor. The scope of your remodel and it's goals determines what's best to do. I haven't seen the existing system or the structure so good specific advice is impossible.

Do you like the look of the radiators? Are they a key part of the structures charm? Do they fit with your new vision? I can't tell you how well sized they are for the structure but it's not a bad assumption to think they are if they are all 1920's originals. They knew what they were doing back then. If you do like their looks and placement, using the system as it is as a back up costs little. If the steam system works well but will be oversized for the newly insulated structure it might be worth living with the less than ideal sizing as your use will be very limited

If the new ducted split system is done well, you will very rarely need a back up system.

Note: the existing appliance that makes steam is not a furnace, it's a boiler.

My forced hot water investigation suggestion makes little sense to do if the system is to be used just as a backup. Many smart folks here insist it is never really worth the conversion effort regardless. I believe there are cases when it would make sense. FHW conversion is really not a good idea if the existing steam system works well and is in good condition.

The above debate is about the value of chasing higher efficiency by converting the existing steam to forced hot water and running much lower temperature water in the existing radiators trying to get max theoretical savings over the old steam system.

Another option is to replace an oversized steam boiler with a smaller one to better match the new remodels reduced heating loads.

If you hate the radiators you can re-home them during the remodel and create a new backup system related to the new duct system.

We all seemed to agree a backup system is very wise to have. I think during the remodel is the time to commit to one or the other or none. Leaving the radiators in place unused is odd but it costs nothing.

One back up option is adding hot water coils in the duct system. That might make sense if it works with your new domestic hot water production plan. Of course FA furnaces are an option and so is resistance electric heaters. Being able to use a generator to power the back up system is desirable to some. In deep cold weather while experiencing a prolonged power outage you would get cold fast and frozen pipe damage is possible.

It's best to find a skilled person who can look it over, understanding your goals and priorities. They should be able to explain the advantages and draw backs of all the reasonable options and then develop a plan that they think is best and will stand behind.

LRCCBJ

I might add that the "lost" heat sometimes regarded with horror for a steam boiler as it is coming up to steam or a cold start hot water boiler, or the "lost" heat on a hot water boiler held warm for DHW, is NOT lost heat, unless the boiler is in a separate, isolated building.

The standby losses from all CI boilers are massive UNLESS the boiler is sitting in conditioned space. If it is in unconditioned space, none of the energy disposed of by the standby loss is captured or utilized in the building. NONE OF IT.

We have had this discussion before and you cling to the false premise that, by some miracle of physics, the energy in the colder basement will magically rise up into the warmer first floor rather than eject itself in the most favorite place…………….the basement walls above ground level……………which typically have an R value of .8!……………as compared to the insulation beneath the first floor which might have a typical R value of 15 or so.

Jamie Hall

Most basements are at least partly conditioned…

And heat can, and will be, lost through the first floor floor into the basement. To suppose it will not be is, well, wishful thinking. The heat flow rate will be, as it is through all physical barriers, determined by the temperature difference between the two sides and the construction of the barrier, and heat transfer is by conduction.

This is not to say that insulating the basement walls may not be a good thing, at least in colder or more humid climates. It will be, but, as the previous post noted, that is rarely done.

ChrisJ

https://forum.heatinghelp.com/discussion/comment/1808779#Comment_1808779

My boiler and it's insulated pipes are much closer to the uninsulated flooring above than the walls. It is very close to the concrete floor, so I'll give you that.

But I bet a majority of the loss does in fact end up in my house.

That and the warm floors are quite nice from it.

Jamie Hall

If you have any doubts about the heat from the boiler getting into the first floor… just go looking for your cat on a cold winter day.

ChrisJ

https://forum.heatinghelp.com/discussion/comment/1808795#Comment_1808795

I don't know what kind of wimpy cats you have, but mine lay right on the steam radiators.

Well.

One of them does.

JakeCK

Speaking of cats. Mine are currently PO'd at me something awful. I installed a french door set between the new under construction playroom and my new man cave. They have now lost access to over half the basement. Soon they'll loose access to the boiler room as well.

They are not amused.

ChrisJ

https://forum.heatinghelp.com/discussion/comment/1808812#Comment_1808812

-5 points for using the term man cave.

LRCCBJ

https://forum.heatinghelp.com/discussion/comment/1808782#Comment_1808782

Of course heat will be lost from the first floor into the basement. That is the entire point. None of the energy delivered by the boiler to the basement ends up in the first floor. To attempt to argue that the basement is warmed sufficiently by the 10K loss of the CI boiler (when it is operating) to result in any reduction of heat transfer between the first floor and the basement is simply ridiculous.

I will state it again to help you to understand:

All of the energy lost to the basement by the CI boiler ends up outdoors via the foundation wall below the sill plate and above the ground level. The R value is effectively an open window.

DCContrarian

Here's a thought experiment: if the boiler were off, and the first floor were being heated by some other method, what would the heat flow look like?

The basement would be quite cold. The floor of the first floor would be quite cold, and some of the heat from the first floor would be lost through that floor into the basement.

So when the boiler is running, the opposite happens. If the basement is warmer than the first floor, heat is flowing from the basement to the first floor. If the basement is cooler than the first floor, heat is flowing from the first floor to the basement, but not as much as it would if the boiler weren't running. So the amount of heat being lost by the first floor is less than it would be if the boiler weren't running.

In that case, is the boiler contributing to the heating of the first floor? It's a question of semantics.

ChrisJ

https://forum.heatinghelp.com/discussion/comment/1808818#Comment_1808818

All of the 1950s-60s slab ranches with an uninsulated slab are a perfect example of that.

JakeCK

You're both right. :p The answer to the riddle is to insulate the basement and bring it fully into the thermal envelope of the building.

There argument averted.

JakeCK

@chrisj Why's that?

Jamie Hall

Not really semantics — though one could look at it that way.

The problem is the usual one: failure to look at the entire structure and its heating system — whatever it may be — as a single integrated system. It starts, of course, with the reluctance of people to do a heat loss calculation. And it goes on from there.

The basement and boiler wasted heat claim is one of the most common errors which results, but is by no means the only one.

One of the more entertaining current ones is putting a heat pump water heater into a conditioned space. A brief review of the thermodynamics of that one will show that the heat which the heat pump water heater is putting into the hot water must come from whatever is heating and conditioning the space — resulting in no net improvement from the HPWH in overall energy use (before someone yells at me, yes, in the summer time, the HPWH will help cool the space, so that may be a gain — I was referring to or thinking about heating…)

A heating system, in short, is a SYSTEM, not a collection of components which came off the truck.

JakeCK

https://forum.heatinghelp.com/discussion/comment/1808824#Comment_1808824

Except my almost 40 yr old boiler is more efficient than a standard gas water heater and has excess capacity. And changing out the water heater allowed me to remove an entire flu/chimney. One less very large hole going straight to space.

With the high insulation level of my basement and all of the server equipment I'm actually fighting to keep my basement cool both in the summer and shoulder seasons.

DCContrarian

https://forum.heatinghelp.com/discussion/comment/1808821#Comment_1808821

Which is what modern codes require.

LRCCBJ

https://forum.heatinghelp.com/discussion/comment/1808818#Comment_1808818

Please tell me that you have observed an unfinished (and unheated) basement that is warmer than the first floor simply due to the operation of the boiler. In 50 years of observations, I have NEVER seen one.

You would need to find a basement that is 20% of the square footage of the first floor with the boiler sitting within. One in a million. And, in such a situation, the transfer to the first floor is only for a small fraction of that floor.

It most certainly is not a question of semantics.

bburd

LRCCBJ said:
"Please tell me that you have observed an unfinished (and unheated) basement that is warmer than the first floor simply due to the operation of the boiler. In 50 years of observations, I have NEVER seen one."

I agree that such cases are very rare and becoming more so, but I've seen one: my grandparents' house near Boston, built in 1916. Three stories, no insulation, well weatherstripped single pane windows. One pipe steam, 19 column rads, 990 SF EDR. Smith Mills all fuel boiler from the early 1960s, firing oil at 3 GPH. Fully air cell insulated steam pipes.

The unfinished basement was 80° in the dead of winter, with the first floor thermostat set at 70. There were no radiators down there.

My other grandparents lived in a colder climate in the western end of the state, in a smaller house built in 1939. They had storm windows. One pipe steam, 10 tube style radiators, probably 450 SF EDR. Original Burnham all fuel boiler, firing natural gas with a single port upshot burner. Steam pipes fully insulated. Generally speaking it was at least as warm in the basement as it was upstairs.

I think this had to do mostly with the large size and thermal mass of older boilers originally designed for solid fuel, in addition to the higher loads in uninsulated older homes.

Jamie Hall

Cedric keeps his part of the basement of his home around 50 in the winter time. And considerably less humid than it would be otherwise — which is, on the whole, a good thing, as there is a good deal of food storage down there, not to mention a woodworking shop.

So the temperature gradient from the first floor into the basement is only 12 degrees F. In contrast, the slightly newer (1893) section of the basement drops to about 40, and sometimes (worryingly — there are water pipes in there) slightly colder.

Now the heat loss from the first floor into the older basement is only driven by the 12 degree difference, and isn't all that much. The heat loss into the slightly newer basement is driven by a 22 degree, more or less, difference. Since the floor constructions are very similar, the heat loss into the newer basement is twice as great, per square foot, as into the older basement.

And please, please don't try the argument that "heat rises". You are not talking about some magic ether here. You are talking about conductive heat loss, and the direction is always from hot to cold. Up, down, sideways — makes no difference at all.

If you fail to consider the entire structure as a system, I can see how one might be misled. However, if you do it should be immediately obvious that the warmer basement will mean less heat required to heat the first floor — and that therefore the heat "loss" which is keeping that basement warmer is not a loss at all, but is simply heat being used in a different place. Usefully.

I would agree that it would be a loss — if the boiler was outside in the cold winter air. But it isn't. It's inside the conditioned envelope.