Combi Boiler Hotwater query

daveyjp

Unless your boiler is in a cold environment (such as outside as is more common in mainland Europe) or there is a very long pipe run pre heat is often a waste of gas.

I'd turn it off and see if the wait for hot water is an inconvenience.

twokcc

Recently had an extension built which resulted in almost a doubling of the no of radiators. Existing property had bathroom and ensuite supplied from a valliant ecotec pro 28(installed new approx 2 years ago before I bought the property). Extension included a further en suite. Had 6 or 7 qoutes for extending the system nearly all of these recommended an upgrade to larger combi boiler(approx 40KW?) to enable adequate hot water heating for more than 1 shower. Went to look at a 3bed semi show house =only for ideas- but noted that the house with 2 showers(1 bathrom and 1 ensuite) had a presurised hot water system with a seperate hot water cylinder. However the boiler was considerablely smaller-about 20kw- from memory. Further investigation resulted in finding that pressured hot water systems require the installer to have specific qulificatioons to install pressured hot water cylinders/systems. 5 of installers weren't qualified to install such systems and therefore recommend a large combi boiler to meet the needs when 2 showers are running.
IMO many installers recommend larger combi systems that aren't the best solution for the home owner. pressurised hot water ystems are more expensive but if new build housebuilders go to the expense of installing them in new houses it would seem that they are the best solutions for a more than 1 shower home

unclebulgaria

Dave_save wrote: »

The Worcester Bosch DT20 and DT20RF (wireless room thermostat type) is compatible with Worcester's Greenstar condensing combi and system boilers. On a combi boiler, such as the OP's, you can only control the pre heat periods using the timer. What you are suggesting is that the OP ignores the facility he has for timing the pre heat function, and instead leaving pre heat permanently 'on'. I've always considered saving whatever I can, so the timer is only set for pre heat for those periods when it's likely we'll use hot water. I've had the boiler for 4 years so far. Pre heat is on for around 6 hours per day, so I'd think any savings I've made overall must be worth it, although I've never quantified it.

No I think you miss understand me, what I'm saying is the hot water function of the DT 10 doesn't actually do anything in regards to the hot water side on a combi. The plate heat exchanger contains a small amount of water and the preheat function heats this small amount to a certain temp to increase the speed at which you receive your hot water through your tap (personally I think its blooming useless as the times are negligible IMO) as far as I can remember it doesn't work on a combi boiler but I'll check with my Worcester rep tomorrow as its been a while since I fitted one and they may have updated it.
Ive just re-read the instructions for the DT10 and I think I may be wrong about it running the pre-heat. Hands up! lol