Posting a message to the forum will remove the above advertisement
  1. This site uses cookies. By continuing to use this site, you are agreeing to our use of cookies. Learn More.
  2. Checkout our Plumbers Insurance area - heavily discounted Public Liability Insurance and Van Insurance specifically designed for plumbers.

Discuss S plan/Y plan hybrid system needs a name in the Central Heating Forum area at

  1. Ric2013

    Ric2013 Plumber Top Contributor!!

    So I've decided I will be converting my system to a low loss header (well, close-coupled tees as I'm cheap) and running the UFH off one pump and the rads and cylinder coil off another. With a pump on the primaries, that is three pumps (to make up for the fact that the new pumps are more efficient lol).

    Conventionally, this would be an S plan plus, but that means selling my old and currently functional 3PV for a pittance and then buying two more 2PVs and I don't really trust buying used zone valves on ebay.

    Two options. One is does anyone fancy trading me a used 2PV known to be in GWO for my used Danfoss HSA3 (currently in use in my own house and GWO) and then I only need to buy one 2PV and go for S plan? This is boring, but it would be sensible.

    Other option is to throw a relay into the mix and an anti-gravity valve near the radiator/coil pump and I could get away with keeping the existing 3PV and the 2PV for the UFH.

    I was going to call this the S plan for 'stupid plan', but Sundial beat me to it by a couple of decades. Can't name it after myself as that's too pretentious, but fairly sure that R-plan 'relay-plan' is unclaimed.

    Thoughts, serious or otherwise?
  2. ShaunCorbs

    ShaunCorbs S. Mod Trusted Plumber GSR Top Contributor!!

    Just need one port valve

    Use the pumps on the circuits and a nrv on the returns one each

    Then use a relay for each pump

    Only problem your going to have is summer time when you want hot water the heatings going to come on

    So you would need 3 pumps

    Williams are sell a s plan system for cheap atm (clearance section)
    • Like Like x 1
  3. Ric2013

    Ric2013 Plumber Top Contributor!!

    I make that four pumps? UFH, DHW, RADS, boiler loop.

    You'd use only one 2PV? So where would you put the 2PV?

    I like the fact that you are looking at this from a different perspective from mine.
  4. Jimmy18

    Jimmy18 New Member

    How big is your system?
  5. Ric2013

    Ric2013 Plumber Top Contributor!!

    1.4 kW UFH; cylinder coil; and 5 radiators most of which aren't turned on. 8kW boiler.
  6. Jimmy18

    Jimmy18 New Member

    Why bother with a low loss header or close coupled tees? Waste of time. Stick with 2 two port valves and a 15/60 pump for the rads and hot water. Your ufh needs a zone valve also if you have a stat for it. That would be more than adequate. I’d be more concerned with just a 8kw boiler unless you have like 3 rads...
  7. Ric2013

    Ric2013 Plumber Top Contributor!!

    I suspect you think my house is larger than it is? As I said above, I have 5 rads (but I only have 2 turned on, combined output around 1.2kW), plus 1.4kW UFH.

    Heat loss for this house at full design temperature and -1C outside was about 5.5kW (IIRC) and that was before I insulated the floors. I find the full design temperature far too warm for my liking so my lounge is currently just under 18°C

    8kW boiler is overkill in this house as would be a 15/60 pump. I'm currently running a UPS2 15/50-60 on PP3. Old pump was 15/50 on fixed speed 2, but that was a relic from the system before I improved the pipework considerably.

    I intend to install a thermal store eventually, so the LLH will do for now as a cheap alternative that can easily be modified to a thermal store setup at a later date. Running an 8kW boiler at 0.6kW as required by the bathroom radiator seems like abuse, and I wanted to try this to see how the LLH would affect the system efficiency (currently very low in summer) and boiler cycling behaviour.
    Last edited: Dec 6, 2018 at 10:13 PM
  8. ShaunCorbs

    ShaunCorbs S. Mod Trusted Plumber GSR Top Contributor!!

    system boiler ?
    • Agree Agree x 1
  9. Jimmy18

    Jimmy18 New Member

    I didn’t catch the 5 rads. Sorry. 15/50 pump is more than adequate. Why have you only got two rads on? Ufh is how many circuits/rooms? You don’t need hydraulic seperation on such small system. Why do you think you need it?
  10. Chuck

    Chuck Active Member

    R-plan = ridiculous-plan?

    Seriously, for the low level of energy consumption you are talking about you should check that an electric system wouldn't have a lower total cost of ownership.
  11. king of pipes

    king of pipes Trusted Plumber GSR

    What boiler and cylinder do you have ric you could be making this a bit more complicated than it needs to be post a couple of pictures of what you have bud. Kop
  12. Ric2013

    Ric2013 Plumber Top Contributor!!

    Heat only

    I dislike a heated bedroom, so I only heat the ground floor UFH (2 circuits in one room), as well as the bathroom radiator. Due to open staircase while I'm doing some work, the landing upstairs is also heated to prevent the heat from ground floor rising, but that rad will be off once the stairs are boxed back in. Boiler is running at extreme part load and cycling. I think the LLH would allow a minimal flow rate. This could be ensured with a bypass instead, but I can't see how I can ensure the minimum flow required when only the UFH is running as the UFH pump is, obviously, behind a mixing valve. I also suspect a LLH would prolong the life of the boiler by making it run under more genial conditions.

    I like 'ridiculous-plan'! I would devalue the house and making it even less energy efficient by switching to electric heating. As it is, I have the boiler and it works well and has been reliable to date (2 breakdowns in 10 years), so I'm happy to stick with it rather than spend money on an electric boiler and wiring it in.

    Potterton Netaheat Profile. Cylinder is a standard 117l indirect vented cylinder. Can post photos but they wouldn't be interesting, I suspect.
  13. Chuck

    Chuck Active Member

    I was thinking about ditching the boiler altogether and replacing the radiators with electric ones. You're talking about using very small amounts of energy for heating and a large proportion of this will presumably be hot water. Your current system is an inefficient old and short-cycling boiler that needs annual servicing and will need replacing at some point. Leccy may not be an appropriate solution in your case, but IMO it's worth considering even if you end up rejecting it.
  14. king of pipes

    king of pipes Trusted Plumber GSR

    False economy ric as chuck has said your boiler is old and not fuel efficient you would better to upgrade your whole system even 1mm of scale in the hot water cylinder will stop the exchange of heat through the coil wasteing energy it really depends on your personal circumstances which way to go. Kop
  15. Ric2013

    Ric2013 Plumber Top Contributor!!

    Grid electricity is inefficient even if electric heaters are efficient. I agree it would be interesting to compare the actual heat given out by the boiler vs gas consumed and try to compare the overall environmental impact of grid electric vs gas in my circumstances, but that would require expensive data logging of my system, unless I can hire such equipment.

    I will obviously powerflush the system. Not checked the wiring regs to see if fixed electric heaters could legally be fitted to the ring mains or not, though in practical terms I know the electrics here are very good and would take it easily. Whether the REC fuse on the incoming main would be sufficient is more doubtful, so an upgrade might add to costs.

    In any case, existing radiators are watertight, existing UFH works, existing cylinder works so not happy scrapping the lot to install a whole new system of standalone rads. My limit would be electric boiler or thermal store heated electrically.

    Viessmann combi would be good in this house but I don't know a single gas installer locally (Colchester) that is truly any good even going by recommendation. In any case, I spend perhaps £400 a year on gas, so a new boiler would pay for itself never from the fuel savings. Environmentally, perhaps, a new boiler would weigh up well but as others have previously suggested, we don't know for a fact what the embodied energy/carbon of a new boiler is.

    To be honest, though, what I really want is a wood stove with thermal store, so it boils :) down to what I can do for minimum effort in the meantime.
Similar Threads - plan plan hybrid Forum Date
Ballancing an S Plus Plan heating system Central Heating Forum Yesterday at 10:44 AM
Package Sewage Treatment plant maintenance contract. Plumbing Forum Saturday at 6:32 PM