totally new HVAC system or replace boiler?

7 Replies

Hi all,

This is my first post but I have a question. I dove into my first project back in April. I still have not decided if I should flip it or hold it. I like the area and believe there is a strong possibility of appreciation and feel that getting the experience of land lording will be a good learning experience. However I need to make the place habitable and do to do that I need to install a new steam boiler the old one is broken.

This is where I ran into my 1st hicccup. The town that the property is in wants a heat loss study done. This will apparently cost me $1,500 dollars. The installation of the boiler is another $6,000. Has anyone ever heard of such a thing where in order to replace an existing boiler with one of the exact same model you have to pay an engineer $1,500 for no reason? what is my actual downside on trying to replace it without the study?

I felt like the heat loss study was such a pain that I should look into a central air and furnace system. The house has no ducting or no attic so that is eliminated. I am now looking at a mini split system which would give me AC and heat and be very efficient. I got a quote that said it would be $26,000 to put this system in.  Now I guess the question is would the mini split system raise the value of my house by more than $18,000 ($26,000-$8,000).  


There is 1 more hiccup. The pipes in the house are relatively old and the house was winterized and thankfully there have been some very minor but fixable leaks, however, the radiators look like water has come out of them I cannot tell if they are in good shape and the technician said the only way to know is when you hook up the boiler. So I am worried that if I hook up the boiler I am going to have broken radiators and god knows what that will cost to replace. I am looking for any guidance here.


thanks to everyone on these forums

I confronted this same issue and went with the mini splits, but I am not sure that I would do so again. 

The boiler will be cheaper, and radiators aren't that expensive. The minisplits will offer air conditioning. That said, I wouldn't install the minisplits without an aggressive insulation and air sealing program. Otherwise the house will have a lot of hot and cold spots. @Roy N. is the resident expert on this process.

@Seth Borman - thanks for the shoutout, but "expert" is unwarranted and might be set lofty expectations.


@Harrison Cook

Your post kindles lots of questions.

In the "good old-days" most heating systems were vastly oversized for the building they were heating - energy was relatively cheap, insulation was non-existant to poor ... so it was easier and safer to {drastically} oversize.

Today, while energy {in North America}  is still relatively cheap for the moment,  we have a much better understanding of how to make buildings more efficient {though you might not think so looking at the construction industry in the U.S.A. and Canada}  and there are often more cost-effective measures than simply replacing an old, over-sized heating plant with a new, over-sized heating plant.

You really need to - or at lease should -  perform a heat load analysis to properly size your heating system, a component of which, is determining the rate of heat loss of the building envelope.  Even if you decide to switch the nature of the heating system, you should, and still may well be required, to perform this analysis.

A detailed heat-loss model will also help you prioritize and plan improvements to the building envelope - such as air sealing and insulation.

A few missing bits of information,  which may assist the BP community to provide you with some helpful ideas, include:

  • size and organisation of the building: SFH, duplex, triplex, etc.;
  • characteristics of building: stick-build, {structural} masonry,  number of stories, nature of foundation, basement/crawspace , type of roof, etc.;
  • age of the building;
  • have there been any updates to the building envelope over the years (insulation, vapour retarder/barrier, fenestration, etc);
  • are the radiators the older, freestanding cast-iron type, the mid-century baseboards, or the more modern flat(ish) panels;
  • are the hydronic heating lines copper, black iron or {red} brass?
  • what is the scope of your planned retrofit?  i.e. are you opening walls to update electrical and plumbing, changing floor plan, etc.

All the above will play into deciding the direction best pursued and whether to opt to replace the entire heating system (and with what) or to repair and retain components of the existing system.

1224 SF 2 story single family home.

I think it is a stick build but i am not sure what you mean there.  It is a wooden house with aluminum siding and a flat roof. There is no attic. the basement is unifinished. the home is connected to a natural gas line.

built in 1960

no updates to the building envelope

old cast iron radiators

black iron

I do not plan on not opening any walls.  The house has pretty good bones. I plan on painting it getting rid of all the cosmetic deficiencies and reconnecting all of the utilities. the city should be reconnecting the gas next week as it was cut off at the street when the house was foreclosed. 

@Harrison Cook

A stick built house from 1960 is not terribly old  ... definitely young enough that one would expect to find finned hydronic baseboards and not cast-iron radiators with a steam / gravity fed boiler.

When it comes to your building envelope, if it has not been updated, you may have early paper-backed, fibreglass batt insulation, but could quite possibly have paper-encased gypsum insulation ... in either case, it is likely no more than R5-R7.  It is also likely there is no vapour barrier - and if there is, it's almost guaranteed it is not fully sealed.

Windows, if original, are most probably built in-place with single glazing (no thermal panes) and no gaskets or weather stripping {read: they probably leak).

If the electrical has not been updated, you very likely have ungrounded wiring, though it is possible you may have early grounded (NMD-3).  This wiring is rated to 60C cannot handle the level of heat created my many modern (pre LED) fixtures ... most notably pot lights and halogen fixtures.   You would also still have a fuse box, unless it has been replaced with a breaker panel.

On the plumbing side, your main drain lines and stack are likely cast iron and would be 70-75% through their serviceable life.  Smaller drains may be copper or galvanized {which you will want to remove}.  Supply side is most probably copper, though galvanized is possible.

If you were planning to flip the house, you could apply lipstick and pass the need for a mid-life retrofit off onto the buyer ... though if your objective is to make a career out flipping in that markt, you might think differently.

If you are planning to hold this property as a rental then it is in your long-term interest to upgrade as many of the building systems (starting with the envelope) as you can manage before applying the cosmetics.

In your position, if keeping the property as a rental,, I would plan to upgrade the building envelope (walls to R23, roof to R40+), install a proper vapour retarder and HRV.   Once this was done, you may quite likely find your new heating system need only be 50% the capacity of the old one (which means cheaper to acquire).  Couple that with the fact new natural gas boilers and furnaces can be 95% efficient - where your old boiler is likely no more than 60-65% efficient (maybe less) which means cheaper to operate.

If your existing hydronic system is sound (no holes or end-of-life pipes), then it may well be cheaper to simply replace the boiler with a modern, hot-water {not steam} boiler.  If you need to replace pipes and radiators, then the door is open to considering other heating systems.

A minisplit should not cost you anywhere near $26k for a 1200 sqft house. I did a similar project to yours last year and it cost me 6.5k to put in a 4 zone system+ vents into bathrooms.

Price out your system online, find installers willing to quote you a labor only price. When you find that one honest HVAC guy, hold onto him and never let go. In my experience some HVAC guys are worse than used car salesmen. On the same project I've received quotes that were over 150% higher than what my current installer charges.

@Nancy Zhao

While heat-pumps (either air to air or air to water) are wonderful  - we use them quite extensively - those of us in climates which experience *real* winter are normally required to have an ancillary source of heat to cover those periods where the heat pump alone is inadequate.  

When using a heat-pump with a central air-handler we will use a ancillary heating core in the air handler.  Alternatively, we've used installed the heat exchanger core into the plenum of existing natural gas furnaces.   There are similar air-to-water setups that can be used to incorporate a heat-pump into an existing hydronic heating system.

When deploying mini-splits, electric baseboard (EBB) tends to be the most common ancillary heat found here - in many cases that is because the heat-pump is being installed to reduce the operational demand on the EBB - however we have deployed mini-splits in conjunction with a gas-fired central heating system.

A heat loss calculation should cost a few hundred $$ and/or be bundled into the cost of a new system.

If you’re technically capable, you might be able to do it yourself. It’s a bit of a pain and for a newbie will take a few hours, but it’s just measuring and math.

Old systems are most often oversized, which isn’t good for your energy usage nor the quality of heating/cooling in the house. That’s why its suggested/required.

Find another HVAC contractor and talk through the options. All your prices seem really high.