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Slow the flow through electric boiler?
Brad White_9
Member Posts: 2,440
what the electric boiler is doing? Sort of a base load for mild days? Heat sink for a windmill generator? And is it piped in parallel or series before or after the W/M?
What I am getting at is, if the electric boiler (Argo?) is in series it will boost the W/M output almost regardless of temperature because the coils are that hot. If before the W/M it could help pre-heat cold HWR temperatures to keep above condensation. If the electric is for mild weather, maybe you do not care what the temperatures are, your heat output would be less so the temperature would not matter as much. Same # of BTU's, figured as Hot Rod suggested.
As for the pump, the Grundfos high speed matches their Brute single speed I believe they have the same curve labeled as a 15-42 speed 3 AND Brute, last time I looked.
For throttling I would not use a gate nor a ball valve. I like precision and would use a Tour and Andersson Wye type metered balancing valve. Armstrong, Oventropp, Victaulic also make similar valves. Tunstall is going to market one from Macon I believe. Point is there are several of this type. Select on flow rate (your best guess to start) not pipe size necessarily.
These valves are short money and accurate, just make sure you use the "4 full turns open to closed" model, not the "one-turn" model. With the 4-turn valve you have 1440 degrees of balancing potential (360 x 4). With a ball valve you have 90 degrees and only those beyond 45 degrees does any real work.
Gate valves are really only used for shut-off valves and for water systems are best viewed at the Smithsonian IMHO...
Throttling in general is only hard on the circulator when it places its operating point high on the curve (high head/low flow). They can take it but you have to know if you are close to the edge. Overheating of the pump may result but you will hear noise before that point as it struggles. Mostly though, it is wasteful of pump energy, you "make it to brake it" essentially.
You should not be near this point, I would hope.
For this reason I would hope to see the electric boiler piped in parallel with the W/M flow path. Any bypass should go around the W/M so it does not act as a reverse heat exchanger (unless you want to keep it warm-ish?).
To start the balancing, I would use the taps that are part of the valve (Pete's Plugs essentially) and a needle digital thermometer. Put a Pete's Plug on the return side too and use delta-T as your primary measuring variable. Start with the balancing valve full open and throttle down a little bit at a time while monitoring the temperatures.
If the Electric is piped in parallel then you will not have to re-adjust for W/M-required flow.
You can do pressure but need an accurate pump curve plus system curve. Unless you use a digital gauge, dial gauges will not give you the accuracy you need for what have to be low flows.
Hope this helps!
Brad
What I am getting at is, if the electric boiler (Argo?) is in series it will boost the W/M output almost regardless of temperature because the coils are that hot. If before the W/M it could help pre-heat cold HWR temperatures to keep above condensation. If the electric is for mild weather, maybe you do not care what the temperatures are, your heat output would be less so the temperature would not matter as much. Same # of BTU's, figured as Hot Rod suggested.
As for the pump, the Grundfos high speed matches their Brute single speed I believe they have the same curve labeled as a 15-42 speed 3 AND Brute, last time I looked.
For throttling I would not use a gate nor a ball valve. I like precision and would use a Tour and Andersson Wye type metered balancing valve. Armstrong, Oventropp, Victaulic also make similar valves. Tunstall is going to market one from Macon I believe. Point is there are several of this type. Select on flow rate (your best guess to start) not pipe size necessarily.
These valves are short money and accurate, just make sure you use the "4 full turns open to closed" model, not the "one-turn" model. With the 4-turn valve you have 1440 degrees of balancing potential (360 x 4). With a ball valve you have 90 degrees and only those beyond 45 degrees does any real work.
Gate valves are really only used for shut-off valves and for water systems are best viewed at the Smithsonian IMHO...
Throttling in general is only hard on the circulator when it places its operating point high on the curve (high head/low flow). They can take it but you have to know if you are close to the edge. Overheating of the pump may result but you will hear noise before that point as it struggles. Mostly though, it is wasteful of pump energy, you "make it to brake it" essentially.
You should not be near this point, I would hope.
For this reason I would hope to see the electric boiler piped in parallel with the W/M flow path. Any bypass should go around the W/M so it does not act as a reverse heat exchanger (unless you want to keep it warm-ish?).
To start the balancing, I would use the taps that are part of the valve (Pete's Plugs essentially) and a needle digital thermometer. Put a Pete's Plug on the return side too and use delta-T as your primary measuring variable. Start with the balancing valve full open and throttle down a little bit at a time while monitoring the temperatures.
If the Electric is piped in parallel then you will not have to re-adjust for W/M-required flow.
You can do pressure but need an accurate pump curve plus system curve. Unless you use a digital gauge, dial gauges will not give you the accuracy you need for what have to be low flows.
Hope this helps!
Brad
0
Comments
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Slow the flow through electric boiler?
I have a W/M GV-3 as the main boiler feeding the primary loop, and have an electric boiler feeding the same loop. The electric might have a somewhat lower output temperature at the same flow rate. What would be the best way to slow the flow through the electric to keep the temperature up? I've thought of a return gate valve to it's circulator input to send some heated water back again. Is it a bad idea to also have a gate valve limiting flow - is that hard on the circulator? Pumps are Gundfos 15-42 single speed. Is the better answer a variable speed circulator, or the bypass as indicated above? Another Q - Is the fast speed of a multi-speed circulator the same as a single speed - meaning that the other speeds are slower choices? Thanks - Dave0 -
What is the electric
boilers output? KW rating time 3.41 will give you the BTU/hr.
If the electric is the same BTU/ hr output, as the Weil you should not see much difference in temperature output.
You could throttle flow, a circuit setter or plain globe valve would be best choices.
hot rod
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