Biomass CRA explanation.

[CJK 67]

Hi,

I recently installed a Klover PB 35 wood pelet boiler which is installed with a 1000 litre accumulator tank and is piped in series onto an existing s-plan heating system which has around 20 radiators and a 300 litre indirect vented hot water cylinder. Between the boiler and the buffer, i have installed an Esbe "load" or "back end protection valve". I presume that this in effect is to stop a large temperature difference between the flow exiting the boiler and the return coming back to it causing condensation??? Downstream of the buffer tank we have fitted an esbe CRA 240 V actuator on a VRG valve (i think). This is immediently before the s-plan- pump, motorised valve setup. I am not sure about the exact reason for this valve. Is it to maintain the buffer temperature? I am just looking for a bit of guidance on this, especially the valves as i know there are many different types of valves for different scenarios and i am a bit confused as to when and where each individual valve should be installed and why?


Thanks for taking the time to read this.

Chris

 

[Dotty]

Why on earth have you fitted a back end valve? Unless you have got your terminology wrong and fitted a three port to maintain the return temperature.

 

[missplumb]

I assume it's the mixer valve to control the return temperature to the boiler. The only reason for putting a mixi g valve after the buffer is to control the temps to the heating and hot water circuit.

 

[SimonG]

Still trying to understand why somebody would install something that they seem to know nothing about. I know everybody has to start somewhere, but?

 

[Worcester]

Is the buffer installed as two port, four port, or is it actually installed as a volumiser in series?

Big differences in the way they'll work.

Photo / sketch please

How is the boiler configured with it's call for heat - is there a buffer tank control system in place?

Why haven't you approached your installer about this?

 

[Nostrum]

Sounds like either the radiators are taken off before the buffer and the valve prevents the radiator circuit running when not up to temperature or some kind of safety feature maybe? Is the radiator circuit piped in plastic by any chance?

Either that or the boiler and buffer set point is higher than the heating circuit design temperature?

 

[missplumb]

The Esbe mixing valve is there to protect the boiler from cold return temps. The boiler needs to be at 60oC on the return before the valve slowly opens to let the circuit pass through the buffer. It acts as a shunt circuit. The mixing valve after the buffer is to control the temperature of the water going into the system not to keep the buffer up to temp. Maybe the radiators are low temperature and needs to be below the 80 degrees the buffer puts out.

 

[Dotty]

The Esbe mixing valve is there to protect the boiler from cold return temps. The boiler needs to be at 60oC on the return before the valve slowly opens to let the circuit pass through the buffer. It acts as a shunt circuit. The mixing valve after the buffer is to control the temperature of the water going into the system not to keep the buffer up to temp. Maybe the radiators are low temperature and needs to be below the 80 degrees the buffer puts out.

Like I said originally, I hope it's a 3 port valve creating a shunt circuit and not a 2 port back end valve. I'm praying that the op just has his terminology wrong.

 

[missplumb]

Agreed.

 

[Nostrum]

The VRG can be used as a diverter as well as a mixing valve (hence the actuator) which is why it may be piped up with the heating circuit before the buffer.

Looking back at Worcesters post I think he may be implying the same thought with the 2 port buffer?

Perhaps my post wasn't clear last night, I'd just got back from a long day so it was a bit rushed.

 

[Worcester]

The Esbe mixing valve is there to protect the boiler from cold return temps. The boiler needs to be at 60oC on the return before the valve slowly opens to let the circuit pass through the buffer. It acts as a shunt circuit. The mixing valve after the buffer is to control the temperature of the water going into the system not to keep the buffer up to temp. Maybe the radiators are low temperature and needs to be below the 80 degrees the buffer puts out.

what a briliant,succint description would have taken me 4x as many words to describe it , thx