By-pass valve for reducing heating loop

[mmindazz]

Can,t comment on the evohome controls as I have no experience of them.
I have a oil fired boiler which doesn't (and can't) modulate so it and all other oil fired boilers spend their entire lives cycling on/off, I can't find the numbers just now but I was quite surprised at how little the cycling affected the efficiency even with very low heat demand.

I believe that combi gas boiler is not like oil fired boiler

 

[John.g]

You will generally see a minimum flow requirement set for HW flow to ensure that the combi is continuously running when in HW mode, it is probably ~ 2.5 to 3 LPM in your boiler depending on what the max HW temperature intergas allow, possibly 60C?,

 

[mmindazz]

You will generally see a minimum flow requirement set for HW flow to ensure that the combi is continuously running when in HW mode, it is probably ~ 2.5 to 3 LPM in your boiler depending on what the max HW temperature intergas allow, possibly 60C?,

I have maximum 65C on winter, summer time 55c-60C
[automerge]1578328906[/automerge]
I was looking more and more about my system and I find out, that building company installed wrong system at all.

Hereby translated email with googletranslate. I suppose to have this system: no UF pump in living room, independents lines for first and second floor, 2 thermostats, O got nothing.

I would like to know how does the system looks like?
e are pleased to inform you that the floor heating system in your home has been upgraded. This upgrade increases the comfort and improves the energy efficiency of your home.



The renewed central heating boiler offers 2 heating lines: a low temperature heating line for the floor heating and a high temperature heating line for the radiators on the floor. Because the radiators can now also be supplied with a higher temperature, the dimensions are smaller, the room heats up faster and the system uses less energy. The two heating lines can be operated independently of each other, since the central heating boiler is now also operated by two thermostats. One thermostat for the floor heating in the living room and one for the radiators on the floor. In combination with the thermostatic radiator valves on the floor, the temperature can be regulated per room. The room thermostat on the floor is wireless and works like a remote control. The thermostat must be placed in the room with the highest temperature demand. When the thermostat measures a too low temperature, the central heating boiler will switch on. With the thermostatic valve on the radiator you determine which radiator heats up at that moment.
[automerge]1578329227[/automerge]

I have maximum 65C on winter, summer time 55c-60C
[automerge]1578328906[/automerge]
I was looking more and more about my system and I find out, that building company installed wrong system at all.

Hereby translated email with googletranslate. I suppose to have this system: no UF pump in living room, independents lines for first and second floor, 2 thermostats, O got nothing.

I would like to know how does the system looks like?
e are pleased to inform you that the floor heating system in your home has been upgraded. This upgrade increases the comfort and improves the energy efficiency of your home.



The renewed central heating boiler offers 2 heating lines: a low temperature heating line for the floor heating and a high temperature heating line for the radiators on the floor. Because the radiators can now also be supplied with a higher temperature, the dimensions are smaller, the room heats up faster and the system uses less energy. The two heating lines can be operated independently of each other, since the central heating boiler is now also operated by two thermostats. One thermostat for the floor heating in the living room and one for the radiators on the floor. In combination with the thermostatic radiator valves on the floor, the temperature can be regulated per room. The room thermostat on the floor is wireless and works like a remote control. The thermostat must be placed in the room with the highest temperature demand. When the thermostat measures a too low temperature, the central heating boiler will switch on. With the thermostatic valve on the radiator you determine which radiator heats up at that moment.

P.S it suppose to be special boiler with 2 burners?

 

[John.g]

No two burners, you will have high temp (at boiler SP temperature) water supplying your rads and a thermostatic mixing valve to reduce this high temperature water to a lower temperature for your UFH, I would think.

 

[mmindazz]

No two burners, you will have high temp (at boiler SP temperature) water supplying your rads and a thermostatic mixing valve to reduce this high temperature water to a lower temperature for your UFH, I would think.

they mention that lines will be separated and can be control each floor, it means suppose be installed mixing valve with motorized valve?

 

[John.g]

I have never seen a UFH system or a combined Rads + UFH but I imagine it would require two circ pumps, one conventional boiler circ pump which would run in any one or combination of rads+UFH, in other words, in all modes, the second circ (& blending) pump would not be required to run if rads only in use.

 

[mmindazz]

Just come back home. Reduced some parameters, one of it boiler maximum load. From 70% went down to 20%, its around 7kw maximum load. If I good noticed I believe he can modulate even lower, after reducing parameters, the water temperature went down to 40C, believe it was minimum load. And it was modulating from 40C to 75C depending of heat demand.

Evohome- I will return back to the shop. This system is not build to every boiler and every home. With evohome my boiler consume more gas than before. One of reason is that it separate rooms in zones and each room controls by it self. It supper nice, but not in my house. Boiler is oversized - one radiator on is 1.2kw, boiler can delivery minimum7kW, tha with evohome system its cycling non stop, starts for 30-60s and goes of, after few minitus its starts. it goes all day non stop. The second thing UF heating - UF pump controlled by BDR91 relay and its starts and stop independently, It runs for 1 minute and stops for 5 min. time changing by heat demand. can be longer or shorter, but the boiler is all the time modulating. So what happens, UF pump runs for 1min, boiler runs to, pump stops, boiler still runs, after 1 min boiler goes of because of return temp. after 5 minutes the pump starts and in no time the line become cold, boiler starts again. And of the day I have boiler starting stopping somewhere around 100 times.
I bring old my system back and compare the boiler behavior with reduced parameters.