freezergeezer
Member
Hi,
I've just bought a modern Heatmiser WiFi Heating/Hot Water programmer for my Heating System which I was hoping would be a simple replacement for my Honeywell ST7100 (which controls the Hot Water Only) and a Drayton SC3 Digistat (which controls the Heating). I've managed to replace the Digistat which had simple L/N/Heating On connections, but am having trouble with the Honeywell which has L/N/DHW ON/DHW OFF connections and they're all wired.
Problem is that I've got no DHW OFF terminal on my new Heatmiser programmer (just a DHW ON).
I've emailed Heatmiser who have told me this... "You will need to introduce a relay with a set of changeover contacts. This will provide a 230 volt supply for both power open and power closed for your motorised valve." which seems to make a great deal of sense to me from a theoretical standpoint.
It seems I have a single three-way valve on my system which, I guess, makes my system a Y-Plan system. I've been reading this forum and other places and have concluded that I really DO need to have a solution for this DHW OFF before I look to get rid of the Honeywell programmer otherwise I guess bad things might happen.
Few questions for the forum, please...
1. Am I right in that I DO need to wire up the DHW OFF somehow ?
2. What's the practical approach to doing this ? i.e. where would I get a "relay with set of changeover contacts" ? is this a Maplin thing, or something made specifically for Heating Systems ? Is it something that is wise to get a qualified electrician to do, or can a competent DIY'er do it ? (i.e. competent enough to add sockets in a house etc.)
3. Any advice on wiring ?
Thanks a lot.
I've just bought a modern Heatmiser WiFi Heating/Hot Water programmer for my Heating System which I was hoping would be a simple replacement for my Honeywell ST7100 (which controls the Hot Water Only) and a Drayton SC3 Digistat (which controls the Heating). I've managed to replace the Digistat which had simple L/N/Heating On connections, but am having trouble with the Honeywell which has L/N/DHW ON/DHW OFF connections and they're all wired.
Problem is that I've got no DHW OFF terminal on my new Heatmiser programmer (just a DHW ON).
I've emailed Heatmiser who have told me this... "You will need to introduce a relay with a set of changeover contacts. This will provide a 230 volt supply for both power open and power closed for your motorised valve." which seems to make a great deal of sense to me from a theoretical standpoint.
It seems I have a single three-way valve on my system which, I guess, makes my system a Y-Plan system. I've been reading this forum and other places and have concluded that I really DO need to have a solution for this DHW OFF before I look to get rid of the Honeywell programmer otherwise I guess bad things might happen.
Few questions for the forum, please...
1. Am I right in that I DO need to wire up the DHW OFF somehow ?
2. What's the practical approach to doing this ? i.e. where would I get a "relay with set of changeover contacts" ? is this a Maplin thing, or something made specifically for Heating Systems ? Is it something that is wise to get a qualified electrician to do, or can a competent DIY'er do it ? (i.e. competent enough to add sockets in a house etc.)
3. Any advice on wiring ?
Thanks a lot.