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JohnMo last won the day on April 5

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  1. But you say at the start of the thread your thermostat makes the boiler run in weather compensation. The idea is with weather compensation is the heating system just gives enough heat to the house to maintain the house temperature. The boiler runs for very long periods. So in theory the zone valves should never close. You are referring to a heating system that runs at very high temperature with on off controls. So in that case the boiler would fire for a short period, the thermostat says the room is hot enough, switch boiler off temperature in the rooms drops, boiler fired up, repeat.
  2. As above, so you have zero need for any zones valves with a combi. Just run as a single zone.
  3. A close coupled tee can be anywhere in a circuit, but you just need to ensure you have flow to the CCT and back to the boiler. I operate two zone one is the house UFH and the other is a summerhouse with fan coil. Both have a thermostat and can call for heat but both have to no longer require heat to shut off the heat pump. I run without any zone valves. If the summer house needs heat the floor of the house is also heated (acting as a buffer). In the last couple of months the house hasn't had to call for heat, as it's always hot enough just because the summer house is calling for heat more often than the house. Energy consumption isn't affected much in fact it's quite good. My buffer, electronic mixer are being removed soon. So it will be ASHP, fan coil and UFH all driven from ASHP pump, two thermostats, either can call for heat, both off to stop heat. So to simplify your system. You run WC, is there any real need for zone valves at all, what do they do (DHW and heating)? Just run long and slow as WC is intended? Your UFH will just need a mixer/pump to drop flow temp down to a suitable level. Leave it to run all the time. Apply KISS to your thinking go back to what you need as a minimum, remove the complication.
  4. I have one and still have the gas boiler installed, although I do use an ASHP. But really hope they do stay banned.
  5. Another thing missed in the article is the notional building performance has been moved to a higher standard also. So mediocre designs are pretty much banned, without loads of solar to compensate.
  6. Not quite "Other ZDEHS solutions include: • 100% Hydrogen – the use of 100% hydrogen is the only current example of a fuel which, when combusted to produce heat, results in negligible levels of greenhouse gas emissions."
  7. Yes referred to phe pump, not sure if the advantage but that's two companies that do. This what my manual says about DHW heating. There is some modulation but not until 1 Deg of target temp. My Atag boiler seemed to operate exactly the same as the heat pump, I noticed if you tried to heat a cylinder (thermal store with heating coil) at too low a set temperature against small coil, it just wouldn't get there instead it would just cycle a lot. Cylinder temperature would remain static, boiler would run for a minute overshoot target and shutdown for 10 mins. I over came the issue with a huge PHE.
  8. You make the assumption that the heat pump modulates during hot water production, mine explicitly states it does not. It runs flat out to get DHW production done ASAP. The warm flow cylinder has a modulating pump speed controlled by the heat pump I believe, same principle as mixergy.
  9. Are rubbish with UFH as you get big under and over swings in temp. The one I mean mentioned is about £60.
  10. The two statements seem to be a contradiction. Don't need need much heat and astronomical to run a heat pump? Basics are if your house needs 3kW at the design day, you need 24 x 3 is 72kWh. Via a panel heater at 30p per unit is £21 per per day. If you design day is -7 and you need 35 water flow, your CoP will be 2.8, so about £7.80. Most other times both will.becway cheaper. Heat pump are either on all the time at a low rate or batch charging at an elevated temperature but only if yiu use a time of use tariff.
  11. Ok, so you two ways to go with UFH attached to radiator system. Slow and steady via a mechanical or electronic mixer. I would go towards an Ivor mixer, they have plenty of adjustments to get things right. Then run at a slow steady rate. UFH when run long and slow can be self modulating. An electronic mixer can be good and expensive, in most cases not really worth the expense. I am saying that as a person that owns one. Have a low hysterisis (0.1) thermostat (Computherm Q20RF for example) connected to the pump stop and start.
  12. I spoke to them last year, if it wasn't connected to their heat pump they weren't interested and said it only designed for their heat pump.
  13. To add UFH your floor insulation needs to be very good, most retrofit are not. Also control really depends on floor buildup and depth of screed. What's the motivation for UFH?
  14. But wired to priority hot water, not both together assume. Grant have a similar setup as standard, but a note saying the timing has to such that both dhw and heating cannot occur at the same time. My cylinder actually came with diverter valve as standard.
  15. 22mm will be fine for that size of heat pump. But regardless I would always go for 3m2 or bigger. The smaller the coil the bigger the CoP hit doing hot water. My 210l 3m2 slimline cylinder takes about 40min to reheat to 50 between thermostat hysterisis set points. 6kW ASHP max flow temp is 56.
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