Boiler/water pressure issues

ThisIsWeird

KaratePigeon said:

FreeBear said:

ThisIsWeird said: 4) Don't replace boiler unless it's just about the only solution - it's just an utter waste of money.

If water flow is low from an electric shower, switching to a combi isn't going to improve matters. Replacing with another gas boiler is not likely to save much gas. Putting in a new thermostat on the other hand, could see a saving of 5-15% if it is a programmable one. And if the boiler can modulate, a thermostat that can communicate with the WB will save a couple more percent.

If you were to replace the gas boiler, I'd seriously look at a heat pump - The likes of Octopus have been giving out quotes that are comparable to the cost of a gas boiler, and some have been significantly cheaper (under £1K for a few).

Thanks - good to know a combi won't help the water pressure, as the engineer didn't really answer that question. I think they just wanted to persuade me to pay them to replace the boiler! My long term plan is probably to keep my boiler for another 5 years or so then maybe get a heatpump, I'd rather wait until a few of my friends have them first so I can see what they are like! I mentioned this to the engineer today too, and he said nah, heatpumps are never going to replace boilers. (again, not sure I trust him as think it's definitely heading that way!) Though maybe it is worth me getting a quote - would that improve my hot water pressure?! I have a small garden so not sure where the heatpump would go or how noisy it would be, which is what is putting me off. 

If your mains supply is good - say at least 15lpm, ideally nicely more - then a combi will sort your issue. That's because your hot cylinder and CWS in the loft will be chucked out, and your H and C will now be delivered at the same pressure = balanced.
However, your shower mixer will still be manual, so always a bit more tricky than most to adjust (but infinitely better than current!)
Swapping to a combi would, tho', be a dramatic solution, as it would be a very costly way to try and sort what is a simple issue.
Two ways I can think of to sort your shower imbalance; one is to take a dedicated cold supply from the CWS to your bath mixer (and only the bath mixer - leave the basin and toilet fed by the mains). That would then mean that the bath mixer gets its hot and cold at the same pressure, so would be 'balanced'.
Or, fit a flange and get your pump working on your hot again. (I wonder how effective these wee inline booster pumps would be - they are around £100 or so?)
Both will be compromised to some extent by the 'manual' bath mixer, tho'. Ie, any change to flow - someone runs a tap/flushes a loo - will cause a temp change.

EssexExile

We've had pumped showers fed from the cold tank in the loft and the hot tank in airing cupboard (with Surrey flange) for years, they're great, thermostatic mixer not required and they're not affected by taps running elsewhere as the supplies are separate from anything else.

On your point about the boiler not turning off, are you aware that they run on for a bit after you turn them off, they don't stop instantly?

ThisIsWeird

KaratePigeon said:

The thermostat is a dial stuck on the wall of the living room, looks like it's been there for many years! No display. It does work though, clicks on and turns the heating on when you turn it, and most of the time turning it down clicks the heating off. Just sometimes it doesn't (mostly when i've been lazy and left it too long so the house is already a bit too warm!) Where is the motorised valve, on the thermostat? The boiler is upstairs in an airing cupboard.

Sorry - completely missed your reply - don't chop me

The wall 'stat - when you say that turning it down sometimes doesn't turn off the heating, does the 'stat still 'click'? And, as Essex asks - do you leave the boiler running for a minute or so to see if it does actually turn itself off? As Essex says, when the system is 'hot' - and you've said you reckon it's when it's been running for a goodly while - then the boiler want's to keep the flow going after it's turned off the flame, so that the boiler isn't left with scalding water inside it. A minute or so should determine whether it's this.

The motorised valve will be in the airing cupboard. If you take some photos, we can direct you to it, and give you some simple checks to try.

Albermarle

EssexExile said:

We've had pumped showers fed from the cold tank in the loft and the hot tank in airing cupboard (with Surrey flange) for years, they're great, thermostatic mixer not required and they're not affected by taps running elsewhere as the supplies are separate from anything else.

On your point about the boiler not turning off, are you aware that they run on for a bit after you turn them off, they don't stop instantly?

The issue with the OP is that the cold water is supplied directly from the mains to the shower,  but the hot is gravity fed from a vented tank.
In your case both cold and hot are fed the same way, (from tanks) and yes a pump normally works very well in this situation

FreeBear

Replacing the vented tank with an unvented one might be an option - This would improve flow & pressure to all hot taps and shower without having to replace the boiler or lots of pipework. Would cost a bit more than just a pump though.

Just for giggles, I'd be tempted to see what Octopus would quote for a heat pump. It would include a new DHW tank plus a few radiators - Have heard of installations under £1K.

KaratePigeon

Thanks for all the replies, I appreciate your help. I think I understand most of it! There seems to be a lot of things attached to my boiler, hopefully it makes more sense to you... 

KaratePigeon

And the lovely old thermostat. For those asking am I sure it doesn't turn off - yes I'm sure, the first couple of times it happened I just waited and the house got crazy hot, was a bit stressful before I realised i could turn off the boiler. It doesn't happen every time I have the heating on though, just sometimes so I can't check some of the suggestions until it happens. 

FreeBear

Don't you just love it when a programmable timer is installed in a position where you have to contort yourself to get to the darned thing....

Replace it and the old thermostat with an all-in-one programmable thermostat mounted in a sensible location - Perhaps consider one that comes with an app so that you can set the times & temperatures from your phone. Just bear in mind that support for apps are short lived and the manufacturer could drop it with minimal notice (Hive and Nest has prior for this).

ThisIsWeird

Good photos, Karate.

If that wall 'stat clicks nicely each way, then almost certainly it's fine. The only way it could keep the CH going is if the contacts inside 'welded' themselves together, and for that it would almost certainly stop 'clicking'.

So, that points quite firmly at the motorised valve.

First, just for your info, these are some of the main parts in there:

And this is the valve:

There's a 'flow' pipe coming from the pump, and this goes into the back of the valve. The valve then has two other pipes coming out of it - the top one supplies the hot cylinder to heat it up, and the bottom one heads off to the radiators.

The valve has a wee plastic indicator/lever on the LH side, and that usually moves as the valve is operated. It can also be used to manually move the valve into its various positions.

Could you take a closer pic, please, so we can see the make and model? Ta.

ThisIsWeird

As FreeBear points out, if you do need - or want - to change that room 'stat, then a 2-channel Hive (or similar) should fit directly in place of that programmer you have, and give you full, App-based, control over both your heating and DHW.

Just something to consider after the main issue is sorted.