Boiler running badly with new Hive (split off from old thread)

9 Jan 2021
Reaction score
United Kingdom
Good evening all and HNY!
Hopefully you would be able to assist.

I have the exact same setup and followed the above and other similar guides.

I had this on system at my previous house also on a dual heating setup and worked well but was on a danfoss tp5000 “i think”

My problem is that the boiler (Ideal Logic Heat H18) worked well on the danfoss TPOne - M (downstairs) and the TPOne B (upstairs) and since I connected the dual hive system the boiler sounds like it is really struggling and when it start for warm water it goes slower and slower till it basically sounds like it labours loads with the odd split second splutter and restart.... no fault codes though. Same with the heating, downstairs heating was relatively fine but upstairs did same as warm water, ran a wile “but a lot warmer than the downstairs (downstairs was about 51 - 60 degrees and upstairs went to 85 ish, without me adjusting anything on the boiler) but it also started to struggle, run slower with the odd stop and restart, again without any errors or fault codes.

I do not believe it is running efficiently at all and do not want to cause any damage to it, please advise.

installation as follows:
Upstairs Danfoss

I utilised the black unused cable as a neutral as the unit was battery powered.

Upstairs hive:

Downstairs Danfoss:

Downstairs Hive:

I taped the old NC2 wire in black, this has not been connected.
I taped the old COM wire in red, this is now with the live wire - for some reason if you remove this, the boiler will power down/die - believe this is the feed to boiler....

Both Neutral wires from N to N
L to L (plus the COM as per above)
NO1 to 4
NO2 to 3

I have reverted back to the danfoss system till resolution found to make sure no damage caused.

Would really appreciate your support

Many thanks

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