Hi all,
I have recently installed evohome in my home. My setup is as follows-
Oil fired condensing boiler.
3 zone valves; upstairs radiators, downstairs radiators, hot water.
21 radiators with TRVs.
8x HR92s and 4x HR81s. All other rads using closed TRVs because we don’t use the room (yet).
2x BDR91 relays. One operates the hot water zone valve using the wireless cylinder sensor. The other operates both heating valves.
NO boiler control. The relays operate the valves, then the valves signal the boiler when they are fully open.
90% of the time it works perfectly, maintaining temps within 0.5 degrees. However it tends to overshoot in the mornings when most zones and HW all call for heat.
My theory is that it does most of it’s “learning” while the boiler is just ticking over to maintain room temperatures, and the boiler never gets properly hot. Then in the morning, when there is a larger heat demand the boiler gets a chance to get hotter than normal, confusing the system and causing the overshoot? Guesswork on my part.
Would installing boiler control help here?
I was wondering if this can be done using the two relays I already have. One to operate the HW, and the other as boiler control, if I manually override the heating valves to the open position. Obviously I’ll have to disconnect the boiler control signal from the valves.
Or would I be best forking out for a third relay and do it properly?
Lastly, I have two zones using a HR91 and a HR92 in the same room. I noticed in the bedroom this morning that the rad with the HR91 was hot while the rad with the HR92 was barely lukewarm. Is it bad practice to mix them in a room? Is it normal for the two rads to operate differently or should they heat up together and operate as one?
Thanks for any advice.
I have recently installed evohome in my home. My setup is as follows-
Oil fired condensing boiler.
3 zone valves; upstairs radiators, downstairs radiators, hot water.
21 radiators with TRVs.
8x HR92s and 4x HR81s. All other rads using closed TRVs because we don’t use the room (yet).
2x BDR91 relays. One operates the hot water zone valve using the wireless cylinder sensor. The other operates both heating valves.
NO boiler control. The relays operate the valves, then the valves signal the boiler when they are fully open.
90% of the time it works perfectly, maintaining temps within 0.5 degrees. However it tends to overshoot in the mornings when most zones and HW all call for heat.
My theory is that it does most of it’s “learning” while the boiler is just ticking over to maintain room temperatures, and the boiler never gets properly hot. Then in the morning, when there is a larger heat demand the boiler gets a chance to get hotter than normal, confusing the system and causing the overshoot? Guesswork on my part.
Would installing boiler control help here?
I was wondering if this can be done using the two relays I already have. One to operate the HW, and the other as boiler control, if I manually override the heating valves to the open position. Obviously I’ll have to disconnect the boiler control signal from the valves.
Or would I be best forking out for a third relay and do it properly?
Lastly, I have two zones using a HR91 and a HR92 in the same room. I noticed in the bedroom this morning that the rad with the HR91 was hot while the rad with the HR92 was barely lukewarm. Is it bad practice to mix them in a room? Is it normal for the two rads to operate differently or should they heat up together and operate as one?
Thanks for any advice.
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