condensing heat boiler or heat pump?

bigJoel

Hello everyone I am newbie in this forum.

I need to replace my heat system from my house (my old gas steam boiler is dying). I want to change from steam to water heat. It is at lot of work but my brother did it last year and he is helping me. I am also thinking to install central AC.the question is Will I be better of with the TWO separate systems (condensing heat boiler and central AC) or Just install ONE system central AC with heat pump. Are they any pros and Cons?

PLEASE HELP.

Since you guys are the experts I will take your recomendation very serious.

Thank You.

Joel

SWEI

As usual, it depends...

On a number of variables:



Will a heat pump sized to your cooling load deliver enough BTUs in heating mode to meet your demand?  If not, how close is it? If you upsize for heating load, will you be short cycling in cooling mode?



Will a heat pump operate (and if so, how effectively) at your outdoor design temp?



Will a heat pump deliver hot enough water to meet your design load using the radiators you have?



Someone needs to do the math, starting with a heat loss calc and an assessment of the radiators' capacity at reduced supply temps.

Jamie Hall

Well now...

I can never recommend attempting to change a steam systemm to a hot water system; there are just too many things that can go wrong, and the advantage is minimal.  Not that it can't be done -- it can, in some situations (not all) -- and sometimes it works out pretty well.  That said, I have yet to see a system where money was saved.



The money is much better spent in updating and improving your steam system, every time.



There.  That's off my chest.



Heat pumps are a different matter.  Provided your outdoor temperatures do not drop too low, they do have very high energy efficiency.  As has been noted, though, if the outdoor temperatures drop too low, a heat pump system has to switch to another source for heat -- which is usually electric resistance.  Which, depending on where you are, can be very expensive indeed.



In your situation, I would suggest that you spend a little time and effort in upgrading your steam system with a nice new boiler (properly installed!) and correcting any problems in the existing piping and venting and traps, and installing a properly sized central air conditioner -- with its ductwork -- to handle the cooling loads.  In my humble opinion, you will be a very happy person doing that.

bigJoel

details

Thank you Swei and Jamie Hall.

Let me explain a little bit more. I don't have heat problem other than the boiler is a 25+ years old I had being patching it up (fixing like gas valve, leaks,etc...) It is time to get a new boiler and i don't want to wait in the middle of winter when finally die on me;having said that I also was thinking to put central air for the first time in the house.

I live in a 1950s colonial house in New Jersey since I want to do heating and cooling I was wondering if One system for both is enough or I will be saving more money with TWO separate system.

If two system is the answer I will prefer doing the conversion to water heat cuz I can add two rooms (office and a sun room) clean the bsmt from all the pipes hanging in the middle (maybe someday I can finish the basement) and save money in the long run.

hope I answer some of your questions.

Thank You again for your help.

andrewd33

Bad Idea!

I am a contractor in NJ and get this all the time.  Someone has an older house with steam radiators, HWBB heat and decide they want to kill two birds with one stone and get heat and air conditioning through the same system.  Being that I install forced air heating all over the place but live in my first house that has cast iron radiators with a diverter tee system, I can still remember the first summer night I slept in the house with central a/c through the attic air handler and said.. "This is what central air conditioning feels like"   When the heat comes up it actually stays up. 

There is one reason and only one reason modern construction houses built in this region have forced air heat with central air and ONLY one reason!  IT IS THE CHEAPEST WAY.  Hydronic heating is far superior to forced air.  That is coming from a forced air guru.  That is why the only homes who have hydronic heat and seperate air conditioning are custom homes now because it doesn't cost the builder much more to switch out two air handlers out for two gas furnaces and evaporator coils.    If builders were to install central air and seperate HWBB heat the price for HVAC would just about double or more before PEX was around. 

Stick with the steam or hot water heat and put an air handler in the attic and drop the ductwork through inside partition walls or closets to cool the first floor.  You will be happy.  As far as a heat pump or ducted forced air you will be surprised at how much bigger Forced air heating ducts in the basement are compared to steam or hot water pipes.  And don't even think you are going to heat a two story house with forced air from the attic.. IT WON"T WORK.  And you will be installing electric or hydronic baseboards right back in to keep you warm downstairs!

andrewd33

Bad Idea!

I am a contractor in NJ and get this all the time.  Someone has an older house with steam radiators, HWBB heat and decide they want to kill two birds with one stone and get heat and air conditioning through the same system.  Being that I install forced air heating all over the place but live in my first house that has cast iron radiators with a diverter tee system, I can still remember the first summer night I slept in the house with central a/c through the attic air handler and said.. "This is what central air conditioning feels like"   When the heat comes up it actually stays up. 

There is one reason and only one reason modern construction houses built in this region have forced air heat with central air and ONLY one reason!  IT IS THE CHEAPEST WAY.  Hydronic heating is far superior to forced air.  That is coming from a forced air guru.  That is why the only homes who have hydronic heat and seperate air conditioning are custom homes now because it doesn't cost the builder much more to switch out two air handlers out for two gas furnaces and evaporator coils.    If builders were to install central air and seperate HWBB heat the price for HVAC would just about double or more before PEX was around. 

Stick with the steam or hot water heat and put an air handler in the attic and drop the ductwork through inside partition walls or closets to cool the first floor.  You will be happy.  As far as a heat pump or ducted forced air you will be surprised at how much bigger Forced air heating ducts in the basement are compared to steam or hot water pipes.  And don't even think you are going to heat a two story house with forced air from the attic.. IT WON"T WORK.  And you will be installing electric or hydronic baseboards right back in to keep you warm downstairs!

Jack

Mini-split heat pump

No ductwork. Keep your steam system operational and push the majority of your heat load onto the mshp. Ac will be done by them also. Great zoning, comfort and economy for both your heating and cooling needs.

Jamie Hall

Oh dear...

First off: you wil NOT save money in the long run by switching to hot water heat.  You state that your heat is satisfactory now, as it is, except that the boiler is old.  Well... that means that the steam system is working more or less correctly, no?  So the only cost we are talking about here is a new boiler and installation.  That cost is going to be just about the same for steam as for hot water.  However, with hot water you are also going to have to repipe the whole thing and, most likely, install new radiation as well, since in your instance it is very likely that the existing radiation is still about right -- given steam input; keep in mind that the output from a radiator into the space is proportional pretty closely to the temperature of the steam or water, minus the room temperature -- thus a steam radiator typically puts out half again as much heat as the same radiator would with hot water.  The difference in efficiency will be minimal -- a few percent.



So.  You will NOT save money by going to hot water.



Clearing out the steam pipes in the basement might be a decent excuse, provided you are willing to attribute the cost to that.



If you are installing central air at the same time, I rather like the idea of a heat pump type system, keeping the steam for the days when the heat pump just can't hack it.