water flow rates in old radiators
water flow rates in old radiators
(OP)
I am going to replace a 40 yr old boiler with a new mod-con boiler. I will be heating with old cast iron radiators. I am going to zone the first and second floors and have a primary zone for the indirect water heater.
I am going to have pumps for each zone.
I am just not sure of the flow rates needed to get the most heat out of the old rads.I want to make sure all the rads in the zone get close to the same amount of hot water.
Thanks,joe
I am not sure if this is the best forum for this question??
I am going to have pumps for each zone.
I am just not sure of the flow rates needed to get the most heat out of the old rads.I want to make sure all the rads in the zone get close to the same amount of hot water.
Thanks,joe
I am not sure if this is the best forum for this question??





RE: water flow rates in old radiators
For further information, take a peek in ASHRAE Handbook.
Thanks
RE: water flow rates in old radiators
ht
RE: water flow rates in old radiators
If they were, pressure wash the inside before you re-use them.
RE: water flow rates in old radiators
RE: water flow rates in old radiators
On the other hand you may be able to set up a cascading system such that the radiation gets high temperature water, then the return goes to heat up incoming air to further drop the water temperature back to the boiler.
Also, the existing heating system may have been oversized and there may be sufficient area on the radiation to provide enough heating with a lower supply temperature.
RE: water flow rates in old radiators
Might have to 'tweak' the reset schedule a little, but it will help bring you're return water temperature down.
Preheat coil on outdoor air is a good 'delta T' point in the system. Another strategy is single pipe layout (twin tees) which can be sized for a more aggressive delta T than a typical system.
Another thought would be to check the capacity of the radiators with a high delta T (180-120) the mean water temperature is 150F, which could be high enough for the capacities you need.
One of the mod-con manufacturer's (Weil Mclein) did an interesting case study where existing radiation (finned tube) was used with a high delta T (180-100) they found that the radiation was sufficiently oversized to allow for the lower mean water temp.
RE: water flow rates in old radiators
Does anyone make a preheater for incoming air??
I expect you are talking of the intake air piping.
I could get a fin tube and run it inside the intake air pipe.Would this be good??
I would be happier to buy one from a supplier that has been making them for years.
Thanks,joe
RE: water flow rates in old radiators
It looks like they were running with about 14 gals/mi. That is the flow rate of the grundfoss 15-42 pump that was on the old system.
I guess that would be a good starting point.
Taco makes a 3 speed pump I might go with to give me some flexablity.
Joe
RE: water flow rates in old radiators