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Phil, Mechanical Engineer
Category: HVAC
Satisfied Customers: 8432
Experience:  Retired HVAC/ Electrical & Boiler contractor. Industrial
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Building a new unit downstairs (basement), and have a couple

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Building a new unit downstairs (basement), and have a couple of conflicting descriptions from two contractors which concern. Also, there seem to be differences in the way they vent the furnace and tankless water heaters.

New living area is 1140 sq. ft. which includes media/living room (23'x22'), galley kitchen [without doors to living/media room] (8'x21'), and bedroom/bathroom [combo, no doors] (14'x17').

SIMILARITIES (between both contractors):
Both agree on the furnace being 95% efficient and condensing, which a manufacturer says is characteristic of all furnaces having a 90% efficiency rating or better. Both contractors also recommend selecting a furnace with lower BTUs; although (1) Delta Mechanical includes recommendations up to 60K, while (2) KR_Design&Construction says up to 45K BTUs; otherwise, the motor may burn up--both say.

(1) Provided a range of models essentially ranging from single-stage and modulating to two-stage with variable speed. Installer is okay with running vents for furnace and tankless water heater up through the roof; although, he described using metal plates that contain a hole for the tubes as they pass through the roof.
(2) Suggests using a single-stage because there are less moving parts and it takes 30 minutes before the second stage kicks in. This contractor has already set up the PVC tubes for the two tankless water heaters (two vents for each, one exhaust and one for fresh-air vent). He rerouted the metal vents (exhaust and fresh air) out through the backyard wall (without any metal plates for neither the furnace nor the water heaters).

COMMENT on "differences": I've read on the internet that in addition to using second stage (100% of the gas flow), the second stage also grossly reduces "cold stops" which commonly occur in single-stage furnaces.
(1) DELTA (company) contractor recommended a range of furnace brands and models ranging from single-stage to 2-stage and modulating. (His 2-stage recommendation also has a variable speed.)

(a) What is your recommendation and why?
(b) Should I be concerned about the absence of these metal plates where at least the PVC pipes extending through the roof make direct contact with the wood roof? (The metal tubes that (2) installed end in some metalic vent on the outside of the rear wall.)
Welcome to Just Answer!.

Sometimes people invent terms like 'cold stops' to describe non existent or marginally relevant issues.

Both contractors have recommended high efficiency units... those cost 2 or 3 times as much to maintain over their life span than an 80% efficient furnace.. and are much more profitable to install....and any cost savings in fuel are less than what is saved by being 10 or 15% more efficient in many but not all cases.... that depends on the climate... tell me which direction you are from the center of the nearest city so I can assess the climate issues.

If your basement is underground all the way around, it could get by nicely with a 45,000 BTU furnace if not less, but 45,000 is the smallest generally available

If your 'basement is largely above ground, 45,000 btu would be a good size unless you are in an arctic environment such as Northern Canada.

I recommend Rheems single speed, single stage, 80% efficient furnace.... it will NOT be quite as comforable or quiet as the 95% variable speed models...but it will be very close to as comfortable. and cost half as much, and cost a tiny fraction as much to maintain over its life span..

We can discuss that according to your preferences.


Your questions:

(a) What is your recommendation and why?

Rheems 45,000 btu 80% efficient furnace if local codes allow 80%.. most do. That is my preference.

The furnace vent and hot water heater vents may be OK, the plastic exhausts
operate at 120F they are allowed to touch combustible material

Attach photo's using the paper clip icon in this dialog box
...... if that fails send the photos to '[email protected] attention: Alumalite

(b) Should I be concerned about the absence of these metal plates where at least the PVC pipes extending through the roof make direct contact with the wood roof? (The metal tubes that (2) installed end in some metalic vent on the outside of the rear wall.)

The plastic tubes that go through the roof can touch wood, thats fine, they need to be fit with metal 'roof safes' that look like metal tee pee's .. if you can send pictures that will be good. The type used depends on the type of roof you have.

Let me know, we can go from there. There are no time limits as long as you continue to rate my answers *positively.

Customer: replied 3 years ago.



I apologize for the delay. Took the photos, but while there, the contractor did some additional work--preferences and code upgrades--that he only now says are extra costs. In the contract and also stressed by him before signing the contract, he states that any additional work must be written of and signed as change orders to the contract along with cost agreements prior to the work being performed. Now we are faced with a list of additional charges, many of which we don't believe are worth the costs.


So with the exception of one, we'd like to forget about what you asked for and focus instead on these new charges. I'll look for a JustAnswer attorney to answer most of the confusing issues, less one, one dealing with the ventilation of the furnace and tank-less water heater. Perhaps, only perhaps, you can answer this one.


Originally, when the proposal had been drafted, the contractor would build the cavity (shaft) between the basement, the next (main) level, short attic space above, and roof on top. An HVAC person would install the PVC vents (exhaust and intake) as well as a "box" on the roof to secure the pipes in different directions (so that exhaust wouldn't be next to a fresh air vent). Prior to the contract, the HVAC person suddenly dropped out of communications (for months now). Contractor agreed to do the installation for that HVAC person, of course, for an additional price.


Here's where things get hot. Although the contact states that any additional work must be agreed upon (signed) change order to the contract, he went ahead and installed the furnace and tank-less water heaters as well as the PVC tubing and box to secure them on the roof. But now he has given us a bill--along with other charges--claiming that the PVC tubing wasn't part of the contract.


CONTRACT essentially states that he will install them and elsewhere says that we are responsible for essentially the more decorative materials, while he, for the essentially rough building materials.


While we believe we could just say there was no change order, we are interested in paying him for what work we would have had done anyway. Although, we don't believe that the installation of these PVC pipes is our responsibility. He even had us pay for the PVC pipes, and after talking it out between me and my husband, we believe those are his charges, not ours.


Any insights? (We believe these charges are the result of him walking onto the sight and discovering that his crew hadn't done enough work to date. So we believe he decided to make up for the financial losses by charging us for whatever he felt he could, in the spur of the moment.


Again, if you are willing, any insights/answers?

Hello again.

I have been in this business for 52 years so far and have seen pretty much everything tried to rip off customers. What you are experiencing is common with bad contractors.

The time to bail out on this person is now, not after he makes further attempts to rip you off... and it needs to be done with witnesses present who are willing to testify in small claims court... and so that he knows that he will not be able to lie his way out of the situation.

Take detailed dated pictures of every detail of the job to date. Have witnesses as you take the pictures. Take pictures of him on the job and of his truck if the attorney you work with on Just Answer recommends it also. Don't talk to him alone or without witnesses again. Meantime tell him you need to hold up the job to tend to a brief emergency. (this mess for instance but you don't need to mention it)

You to not want to push him into threat mode. Some of these guys can do a lot of damage, or threaten damage if you resist their ploys.

You do indeed need legal advice to make this go smoothly.

Your recourse in most states that have contractors licensing laws is to file a claim against his bond. In California the bond is for $25,000. But there are very strict time schedules you have to follow... in most states you have 15 to 30 days to make your initial filing, then must follow up from there. That will be a first step

What you need to be wary of is his ripping out work that he has already done with the threat that you need to pay him for all of the unapproved work... thats a common strategy. Lock him out of the job site while you are off 'tending to the emergency'. when you let him back in, there should be witnesses present and you should have already talked to the attorneys you need.

One of our lawyers here can discuss the broader issues with you and refer you to a construction attorney in your area if the money involved is worth the expense... beyond the expense issues here are the risks of dealing with this sort of person.

So far the 'extra' work he has done does not sound like it should add up to more than a few hundred dollars. PVC pipe is not expensive at all, and it is easy to install... and its not just decorative, it is a key part of the work called out in the contract you signed.. he has no right to call it an extra... such behavior is well beyond rational bounds... this person needs to be handled with the aid of legal advice.



Regarding the furnace and tankless water heater venting.. In order to get a building permit in most areas the installation manuals showing the venting requirements have to be shown to the city building department and then inspected and approved... the work has to be approved before it is closed in and cant be seen... given the legal implications that will be the best approach here.


If no building permit has been taken out the contractor will be in violation of the building code and subject to files and risk of losing his contractors license in most jurisdictions ..


Please send the photo's of the work to date, I can review them also.


The attorney will need the contractors license numbers of all contractors involved, and their liability insurance, and surety bond numbers, Insurance carriers etc. Contractors in most states are required to provide the home owner with this information before starting work.


I will send this now before my broadband has a glitch... We can continue on with the technical details later. Stay in touch. You can rate my work so far *positively at any time, I will keep the question open in that case.





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