increasing boiler temp to get hotter heat from baseboard radiators


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Old 12-26-22, 09:32 AM
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increasing boiler temp to get hotter heat from baseboard radiators

I have a old 3 story house. The heat is working but it seems the hot water heaters should feel a little more than lukewarm. I have a tenant that have complained that his apartment is not getting enough heat. I know on my 3rd floor at one time the heat was not reaching especially when it's real cold outside. I increase my boiler pressure to 25 psi and that help that problem. but I feel the baseboard should get a little hotter. I was wondering if I increase the boiler temperature slightly would that help? I believe it's set now at 180 could I increase it maybe to 185- 190 the most to try help the situation? I have cleaned the fins already.



 
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Old 12-28-22, 07:19 AM
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Do the baseboard pipes have enough vertical give at each end that the elbow could be lifted an inch without difficulty? Then put shims throughout the baseboard to achieve a slight end to end rise (preferably the downstream or return end higher). Install the vent at the high end. This will permit easy venting using a manual screw activated vent, or more reliable operation of auto-vents..

Be sure that the system maintains enough pressure so the third floor pressure does not drop to zero when the boiler cycles off. Installing an expansion tank reduces the spread between maximum and minimum pressure so you keep enough pressure during the off cycle portion and don't blow the relief valve during the on cycle portion.

Consider installing another circulator pump at least for the third floor.

Explain to family, tenants, about maneuvering the baseboard louver (if present) or covering part of the baseboard unit will reduce overheating of some rooms. This is not a fire hazard with hot water supplied baseboards. Depending on the order of the radiators in the loop (sequence), covering one radiator may speed up heating in other rooms.)

(If the third floor thermostat (or any thermostat) keeps calling for heat because it is too cold then the circulator serving that zone should not shut off. The burners in most modern boilers will still cycle on and off.)
 
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Old 12-26-22, 10:13 AM
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Yes, increase the furnace high temperature setpoint to 185. If this doesn't satisfy the tenant, it might have to go higher. Assuming the third floor loop is the longest in length, it also has the greatest heat loss. Also , the greater the temperature differential between the loop piping and their environment, the greater the heat loss.
 
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Old 12-26-22, 11:32 AM
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Before raising boiler temperate, when there is inadequate heat, the first and easiest thing to check and fix is venting air a high point of zones at each element

Boiler level venting/purging will not remove air in many systems. All systems develop air over times that reduces BTU heat output.

A permanent solution is Watts auto vents at high points of each zone, $12low cost, reliable, long term way. Watts has black knob to manually check, confirm venting or turn off. valve Keep a $12 spare Watts to swap in if issue. https://www.supplyhouse.com/Watts-05...Vent-3679000-p

Many other brand of auto vents fail, leak and gave them a bad repudiation.Many other brands of auto vents failed, leaked and gave them a bad repudiation. A common cause of failure tire valves in them has rubber seat that deteriorated then leaked
 

Last edited by doughess; 12-26-22 at 01:54 PM.
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Old 12-26-22, 03:06 PM
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You can go as high as 200f if need be. I would go over that. If the boiler is in the basement and there is 3 floors above, you will need about 18-20 psi.
How many thermostats do you have in the home? If multiples do you zone by circulator or zones valves?
Pictures sometimes can really help.
 
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Old 12-26-22, 08:36 PM
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Raising water temperature above 180F increases scaling, lowers heat transfer of BTUs, increases hearing costs and shortens boiler life.

Among many possible reason of poor heat old Brooklyn home3rd floor is tenant opening windows.

Raising boiler temperature might result in tenant opening windows more. (DH is local Long Islander who knows Brooklyn well)

When heat is inadequate on existing system finding cause and fixing is best solution, not raising boiler temp

Simple suggestion for bleezebob is cut heat loss in building will improve heat, lower cost, etc.
 
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Old 12-27-22, 04:49 AM
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Doughess, you said "Before raising boiler temperate, when there is inadequate heat, the first and easiest thing to check and fix......". How do you check?
 
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Old 12-27-22, 05:34 AM
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I was thinking the same thing. How do you check? But since the Watts auto vent is only about $13 dollars I will just pickup one and change and see what happens.
 
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Old 12-27-22, 12:52 PM
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"Raising water temperature above 180F increases scaling, lowers heat transfer of BTUs, increases hearing costs and shortens boiler life." From post #5.

There is no problem raising boiler temp if needed. Baseboard element are rated to give out app. 610 btu's a foot @ 180 deg water @ 4gpm flow rate which is the norm. If you raise the boiler temp, you raise the btu's per foot of element. Raising the boiler temp will not hurt the boiler as they are made to heat water.

Some examples of what you can expect by the higher temps are below.
DEG.... BTU'S P.F. of element @ 4 GPM flow rate
180.......610
190...... 680
200...... 750
210...... 810
215...... 860
220...... 890

Depending how your system is configured also can make a difference. If you have zones for each floor. If you have zone valves and 1 pump or 3 pumps, 1 for each floor. If broken down with 3 pumps, 007's would most likely be enough. If zone valves and 1 pump you might have to get a different pump with either more head or more flow or both.

As far as your pressure goes to reach the 3rd floor for every lb. of pressure you will get 2.31 ft of rise. Rule of thumb is 10 ft a floor so you are looking at 30ft. 20 psi should be enough. 25 psi will not hurt as long as it doesn't reach 30 which is the limit before it blows. Make sure system is bled of air properly and I don't mdean with high vents if you have a loop system you should be good.

Hope this helps a little.
 
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Old 12-27-22, 02:31 PM
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I have 3 zone valves,3 thermostats and 1 pump. I keep the pressure between 20-25 psi. As you can see from the pic I have a old boiler system but it is still kicking. I will do some experimenting and look into if it is bleed properly. The house is heating up but not as hot as I think it should be. I will also work on sealing drafty areas as well.
 
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Old 12-27-22, 03:08 PM
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To check venting, at high level open vent until only water not air comes out.

Easy to check with Watts auto vent installed. Has black knob to manually check, confirm venting or turn off valve.

Most auto vents do not have knob. Tire type air valve in many leaked then has to be capped off, the reason auto vents got bad reputation
 
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Old 12-31-22, 11:24 AM
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You operate your hydronic loop at a pressure so the pressure drop from the low point in the loop to the high point in the loop insures the pressure at the high point is above 0 psi to prevent air from entering the loop. The gauge in photo of post 1 indicates a pressure of 26 psi and 60 feet altitude. This correlates with the fluid flow principle that there is a pressure drop of 1 psi for every 2.31 foot increase in elevation. Doubt this loop has a 60 foot elevation change but donít know the gauges elevation in the loop so canít comment about loop pressure. This fluid flow principle also applies to the circulation pump for the 3rd floor loop. Assuming the pressure drop is (26-6=20) psi, the corresponding circulating pump head should be (20x2.31=46) feet minimum. What is the head rating on pump for 3 rd floor loop?
 
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Old 01-01-23, 09:17 PM
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The BTU per gallon of water is greatly reduced by the amount of air at heating element.

Before raising boiler water temperature would do a "reality check" and consider chart numbers meaningless wishful thinking until venting all air in systems is confirmed,

i.e.
Some examples of what you can expect by the higher temps are below.
DEG.... BTU'S P.F. of element @ 4 GPM flow rate
180.......610
190...... 680
200...... 750
210...... 810
215...... 860
220...... 890
 
 

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