Modernize Old Boiler System

danielha

I've got a 100 year old house with original radiators and piping. The boiler is probably 20 years old - it's a Burnham Independence IN-8-I which seems to run really well on a single loop. It's also got a Honeywell L8148E aquastat hooked into it, which runs out to a very old, simple thermostat upstairs. The system heats very well, but it's incredibly uneven. I've been thinking of some simple projects I could do to improve the comfort level of the house and the two most common suggestions here seem to be:

1) Add TRVs to all the rads upstairs (which gets probably +10 degrees warmer than downstairs)
2) Install an outdoor reset control

I'm interested if anyone has any other simple suggestions to improve this system. Also, does anyone have some straightforward advice on how to retrofit an outdoor reset control onto this type of boiler - i.e. which would integrate best with the existing hardware?

Leon82

Monoflow, loop, manifold home runs?

Steamhead

Is the circulator working? I'm assuming this is hot-water rather than steam- and a bad circ can cause these symptoms.

danielha

Yeah, it's hot water. Circulator appears to be fine, but I can investigate that a bit more - the radiators get hot fast, however, and then the circulator shuts off. I've had this same issue in another house with a brand new boiler and circ, though, so I think it's just a limit of these old-fashioned systems (uneven heating, that is).

I'm not entirely sure of the piping, but it's all original as would have been done in 1920s appalachia. It appears shutting off one radiator doesn't affect those downstream, so I'm thinking they are home runs from the main pipes.

danielha

I'll also add that the system is almost entirely radiators. There is a toe-kick heater that is pretty ineffective because it only runs when the circulator is on and temperatures are high enough, so it doesn't match the rest of the system well. I'm thinking having constant flow with lower temperatures would probably help this struggling guy out as well.

Ironman

The toe kick needs a low temp aquastat to replace the high temp one that comes with it.

ODR may help, but you can't let the boiler run below 140* or flue gas condensation will occur.

Old systems like yours, with their high mass, have a sort of "natural" reset built into them. On warmer days, the water temp never reaches the limit because the thermostat is satisfied first.

I agree that you've got a flow issue and the circ should be checked.

kcopp

I would wire in a Tekmar control to have the system be weather responsive.
This would allow the system to come slower ,less prone to over heat and save energy to boot.
If it has a lot of cast iron what does it have for boiler protection?

Paul48

I think ODR with a cast-iron boiler is a waste of money. The range of temperature between what is necessary to heat the house for most of the heating season and what can't be allowed to circulate through the boiler is ridiculously small.

You should do a room by room heat loss and radiator survey. You need to know where you stand.

JUGHNE

This was most certainly gravity flow hot water??
Usually turning the valves to what seems to be off will still allow some flow to protect against freezing.
I have a 2 story house that is mostly used as an office on the ground floor.
I don't bleed all the air out of the 2nd floor radiators.
This keeps them from delivering at their full heating capacity.
Occasionally, maybe every 2 years, I drain down the system allowing air to gather in the upper floor rads.
For my case I need to only have the water moving thru the 2nd floor rads to prevent freezing.
The rooms get pretty cool. The bathroom rad is fully bled of air for max heat.

Solid_Fuel_Man

Pics would help

Taylor

SWEI

Paul48 said:

I think ODR with a cast-iron boiler is a waste of money.

Not always.

ODR-controlled mixing paired with a CI boiler works for a low temp emitter system -- most especially one which has a lot of mass.

Paul48

How much advantage does the ODR give you vs. a simple thermostatically controlled mixing valve, at 1/3 or 1/4 the cost?

SWEI

Better control, especially in a high mass system.

kcopp

1.. It will automatically change the temperature based on the outdoor temp. The mixing valve cant doo that.
2 .. it does depend on the control as to the cost. A tekmar 260 will cost a lot more than a simple tekmar 256
3.. You will not get any energy savings w/ the mix valve as the boiler will heat up to the max set point each time it fires.

The ODR is something... not perfect, but it gives him an option instead of just leaving it the way it is.

danielha

So it might be the circulator...it's very hot and I can't hear anything coming from it. I just assumed it was working because the water was flowing, but it could just be convection.

In any case I may replace it just to be safe. It's currently a Bell & Gossett Nrf-22 Cast Iron Wet Rotor. Would it be worthwhile to replace it with a fancier new model or just replace it with theach same?

Ironman

Try a Grundfos ups15-58 or equivalent. But you need to confirm the circ is bad.

EBEBRATT-Ed

Have you checked if the circulator is going off on low limit. Do you have a tankless heater ??

danielha

So, I checked into it some more. The circulator does appear to be working, although it may be wired into an ancient day/night mode timer which may have been confusing things.

The Honeywell L8148E aquastat that's plugged into the boiler is set at 220 degrees...and the minimum it can be adjusted to is 180. Do you think a good first step might be reducing that setting?

One of the reasons the ODR appealed was because I live in the southern appalachians. The temperatures in fall/winter/spring vary drastically from low 20s to mid 60s, sometimes in the same day.

I can provide pictures if anything specific would be helpful.

Thanks!

Ironman

Yes, set it down. The CI rads probably don't need more than 160* on the coldest night of the year.

Pics would be great.

What's your locale?

danielha

I'm in Asheville, NC. I've attached a few pics that I already had...let me know if something specific would be helpful.

BenjaminMadore

I redid my mother's old gravity system with an older oil boiler as a Primary/Secondary system with a thermostatic boiler valve a couple of winters ago and it made a big difference in comfort. Most of the season the radiators barely get warm whereas before some radiators were hot and some never seemed to get any heat except on the coldest days of the year.

EricPeterson

1) Add TRVs to all the rads upstairs (which gets probably +10 degrees warmer than downstairs)

Assuming TRVs would not shut off flow to other radiators, I would install these in the warmest rooms to keep them from overheating.

Then move the thermostat to the coldest room and you will get more balanced heat.