Search the forum,

Discuss Hot water demand effect on central heating for Combi boiler in the UK Plumbing Forum | Plumbing Advice area at PlumbersForums.net

M

MartinPod81

Hello,
We’ve recently moved into a fairly old, fairly big detached house (i.e. fairly draughty, but not too bad by any means) with a fairly new well maintained Worcester combi boiler. We weren’t convinced the heating was working right and then got hit with a £610 energy bill for the first 6 months! Anyway, after some investigation we have found:
The Central Heating “seems” to work fine. The CH water flow temperature can be viewed directly in the display. When the CH kicks in, you can see the boiler water temperature rise and feel the radiators gradually heating up. CH water temperature is set to 70degC on the boiler which it gets to and maintains and all the radiators get nice and hot and heat the house. I don’t have any experience with the rate at which the water is heated - it does seem to take a while but not so much that I think there’s a problem.
The issue comes when there is then a demand for hot water. As with any combi, priority is given to hot water so CH switches off. Once hot water demand ends, there is a pre-set delay in the boiler before the CH kicks in again. However during this period of hot water demand and delay, the CH water seems to lose a lot of heat. When the CH kicks in again, the water temp will be around 5 - 10 degrees less than where it was, it will rise by a couple of degrees and then actually fall by around another 5 degrees before starting to heat up again towards the set point. This seems like a big waste of energy, but ok for a one off hot water demand. But when there are multiple hot water demands over a period of time as with normal domestic use the CH can’t keep up when it kicks back in. It loses too much heat during the hot water/delay phase and takes too long to get back up to temperature that the CH water temperature never gets hot enough to get the radiators anything over luke warm before the next hot water demand cycle causes the CH temperature to reduce even further. Therefore the rooms never heat up but all the while the boiler is working away using energy/costing money.

We’ve had Worcester out and they say there is nothing wrong with the boiler and it’s working as it should, it’s just how this system is in our house. They also said they wouldn’t expect to see a combi boiler in a house our size partly for that reason.

Has anyone any thoughts or comments on this? It can’t be right that we can’t heat our home effectively without having to stop using the hot water. Hot water use isn’t large either, there are 3 of us and it’s just general hand washing, rinsing pots, wetting cloths for wiping surfaces etc.

Thank you
 

Reply to Hot water demand effect on central heating for Combi boiler in the UK Plumbing Forum | Plumbing Advice area at PlumbersForums.net

Similar plumbing topics

Hi, Can anyone advise as to why the cold water to my bathroom keeps airlocking? This originally happened about 12 months ago and has happened 3-4 times since. It’s an upstairs bathroom, fed from a tank in the attic. The tank is about 8 Meters away and feeds a bath, sink and toilet. The tank...
Replies
9
Views
323
Hi all I'm hoping someone can shine a light on this for me Since our stop tap on the pavement has now been filled with sand for whatever reason, we are relying on our property fitted stopcock (this is outside on our garage wall) Unfortunately turning this to the closed position only reduces...
Replies
3
Views
243
Copper pipes, I think its fair to say, is not what it used to be, the copper is getting thin while the cost is going up. Meanwhile, plastic Pushfit seems to be getting better and better, cost and convenience was always better, but now the quality is to, have we reached a stage where plastic will...
Replies
2
Views
240
Creating content since 2001. Untold Media.

Newest Plumbing Threads

Back
Top
AdBlock Detected

We get it, advertisements are annoying!

Sure, ad-blocking software does a great job at blocking ads, but it also blocks useful features of our website. For the best site experience please disable your AdBlocker.

I've Disabled AdBlock