Service Sizing - Ontario

[Mr_T_123]

I'm planning to reno an old bungalow (1950s) in Ontario. It's small (one bathroom) and the current fixture unit load is 11.7. I plan to add a bathroom and a sink, bringing the total unit load to 16.7.

From what I can tell, the house is currently serviced by 1/2 polyethylene into a 5/8" meter. After the meter, the distribution piping all reduces back from 5/8 to 1/2 to the water tank and all throughout the rest of the house.

A couple of questions:

1) Ontario building code stipulates that minimum house service size is to be 3/4". Are renovations grandfathered in here? It will be pretty expensive to upgrade the city line (I believe the city charges around $6500 for a 1" upgrade) from the street to the property line, then I'll have to pay a plumber to bring it from the property line into the meter.

2) In the event I am grandfathered in, it's my understanding that my distribution size from the meter to the Hot Water tank is supposed to be 1". This is based on table 7.6.3.4 which says anything bigger than 16 FU (I'm at 16.7) is 1". Would I run 1" from the meter to the hot water tank, and then reduce it down to 3/4" right before the tank? Is there any benefit to going all the way up to 1" between the meter and the HWT even though my service is 1/2"?

3) I plan to use manifolds with 1/2" runs to fixture groups with less than 4FU (ie. Bathroom 1, Bathroom 2, Laundry Room, Kitchen, Hose Bib). My thinking is I'd run a 1" loop on the cold side manifold (given total of 16.7 FU) and also a 1" manifold (no loop) on the hot side (total FU on hot is 14.2) supplying the 1/2" runs.

4) How bad would the pressure/flow be with a 1/2" service for a 2 bathroom, 1 kitchen house?

I've attached a graphic of what I'm thinking

 

[wwhitney]

Is there any benefit to going all the way up to 1" to the HWT even though my service is 1/2"?

I can only speak to this question in your post, and the answer is yes. Pressure loss due to flow accumulates from all the components between the comparatively limitless capacity of the water main in the street to the fixture. So 10' of 1/2" pipe is worse than 5' of 1/2" pipe, etc.

There is, of course, a point of diminishing returns. To make up some numbers, if at the desired flow rate, the 1/2" lateral drops 20 psi, and a 3/4" supply to the water heater would drop 1 psi, while a 1" supply to the water heater would drop 0.2 psi, there's a benefit to using 1", but it's not significant.

Not sure if the regulations you are subject to would require being more proactive, but a reasonable approach is to size everything you are touching properly, as well as replacing all the existing interior galvanized water pipe (it will be rusty inside and reduced in diameter), and then seeing if the resulting pressure and flow are adequate. If not, then you can look at improving the remaining restrictions.

Cheers, Wayne

 

[Sponsor]

 

[Mr_T_123]

Thanks Wayne, that makes sense. From what I can piece together in the code, it's stipulated that anything over 16 FU (I'm 0.7FU over!) is supposed to be 1". It will be about a 20' run from the meter to the Hot Water Tank/Manifold. Yes, the plan is to replace the galvanized with PEX!

 

[Mr_T_123]

For those wondering, this is what the city got back to me with:

A 1/2" water service is legally existing for many older bungalows and is not automatically required to be upsized just because you’re renovating.



Adding one bathroom to a single-family dwelling is normally considered a minor increase in fixture load and therefore no change would be required to the existing lines.



Upgrades are typically required when a substantial renovation is affecting the entire plumbing system.

 

[Nebojsa]

Good to know.

 

[Jeff H Young]

For those wondering, this is what the city got back to me with:

A 1/2" water service is legally existing for many older bungalows and is not automatically required to be upsized just because you’re renovating.



Adding one bathroom to a single-family dwelling is normally considered a minor increase in fixture load and therefore no change would be required to the existing lines.



Upgrades are typically required when a substantial renovation is affecting the entire plumbing system.

I can agree with the building department. giving leeway to the owner to decide what quality of work a owner wants . really should be mostly 3/4 inside the house if I was repipping id start with 1 and be running at least 3/4 in the heater and out . Thats a generous exception on adding a bathroom but I think youll be ok
typical cold weather places have basements with water meter down there so existing 1/2 inch line is shit work (my opinion ) if you were building the house today but should be ok 3/4 inside the house because its existing is ok , if the entire house is 1/2 inch what can I say its sub standard its below any minimum standard but if the budget is tight and you arent super picky and anal it should function ok . but its a bit substandard no beating around the bush your building department gives you the decision to build how you want. If you have pex type b with lots of fittings or old galvinized results might not be great