What central heating system do I have ?

[Spindles]

Hello and apologies in advance for stupid questions and long winded post. I have a Hive system, and when my CH comes on I have just found out my hot water automatically comes on with it. I am able to operate the hot water to come on independently too whereby the boiler fires up and only the hot water light comes on. My hive status light is blue which I think is set for a gravity fed system.
I also seem to be able to put the Hive system into regular mode (green status light), whereby my CH will come on without the hot water, and vice versa.
My query is what system do I have? After reading a few posts I am now totally confused and I'm worried my Hive is set to the wrong system (gravity).
I have an issue where the boiler is turning off before my CH is getting up to the required set thermostat temperature and just turns off and on randomly taking an age to finally get to the right room temp. Is this a separate issue or is it connected to being set on gravity fed setting? My hot water is scalding.
I have put photos in showing the boiler, motor

ised valves, airing cupboard and the pipes going upwards into the two water tanks above, 1 small and 1 large in the loft
Any advice would be greatly appreciated. As you can probably tell I really don't know much, so hope I have explained enough. Many thanks.

 

[flameport]

My hive status light is blue which I think is set for a gravity fed system.

That is wrong, you do not have a gravity system.

If the HW is too hot, either the thermostat is busted (the grey Satchwell box with the black dial on it), or it's been wired incorrectly somewhere.

I have an issue where the boiler is turning off before my CH is getting up to the required set thermostat temperature and just turns off and on randomly

Unrelated to any Hive settings. There are various other things that could cause that such as a defective zone valve, poor circulation due to blockage, circulator not working properly, and so on.
Given the shoddy wiring mess, incorrect installation is also probable.

 

[Deleted member 267285]

If the hot water is too hot - the cylinder thermostat (grey satchwell) is far too low positioned.

 

[Spindles]

Thanks very much flameport and CBW.
Do I have a pumped system then? I'll change the Hive receiver to the green light setting so the CH and HW work completely separately.

Re. The grey satchwell, could I turn the dial down to reduce the water temperature or is that not advisable?

Re. The spaghetti wiring, I try not to look in that cupboard as it worries me .

Sounds like I'll need to get someone in to check things over.

 

[Deleted member 267285]

Re. The grey satchwell, could I turn the dial down to reduce the water temperature or is that not advisable?

Not advisable. I meant it’s too close to the base of the cylinder.

 

[Spindles]

Ok, thanks very much CBW.

 

[Mister Banks]

As said above the hw thermostat is to low and needs to be approx one third up from the bottom of the tank. I also think the temperature is set a bit high, 150F is 65C so if it was me I would lower it to 140F which is 60C.

 

[Spindles]

Thanks Mister Banks

 

[fixitflav]

Do I have a pumped system then?

It's almost certainly fully pumped (CH and HW). But it could be either gravity, with a feed/expansion tank in the loft, or pressurised, with an expansion vessel. Which do you have?

 

[Spindles]

Thanks Fixitflav. I have a water tank in the loft that supplies the bathroom. I don't think I have an expansion vessel (having googled what it looks like).

 

[fixitflav]

Thanks Fixitflav. I have a water tank in the loft that supplies the bathroom. I don't think I have an expansion vessel (having googled what it looks like).

OK, it's a gravity system.

 

[Spindles]

I'm sorry but I'm so confused. I presume I have a fully pumped gravity fed system then ?If it's a gravity system should I have left my Hive receiver on the blue setting for a gravity fed system. Someone said earlier it wasn't so I changed it.

 

[flameport]

It's a pumped system.

Gravity is typically a large floor standing cast iron boiler with two large pipes going to the hot water cylinder above. Water circulates by convection. When it's heated, it's density reduces, causing the heated water to rise and the cooler water to fall. There is no pump or circulator, and when the boiler is on, the hot water cylinder is heated.
Radiators can also be gravity, or the more usual method for domestic was to add a separate pump just for the radiators. Boiler on = hot water. Boiler and pump on = hot water and radiators. There is no radiator only option as that would be pump on only, which would just circulate cold water. That's why controllers with a gravity option don't allow you to select radiators only, as it wouldn't do anything useful.

Gravity systems like that have been obsolete for decades. There are probably a few left somewhere, but they are neither common or desirable.

The hot water from your taps is gravity - the pressure is only there because of the large cold water storage tank in the loft. However this is unrelated to the boiler and the controls for it.

 

[ianmcd]

You are getting the completely wrong advice from some users , you have a fully pumped system, it may be gravity fed, GRAVITY HOT WATER, and gravity fed are not the same thing, they are completely different, you CAN NOT have a HW cylinder below a boiler on a GRAVITY HOT WATER SYSTEM, gravity fed system is the wrong term it is an open vented system , Gravity HW is a completely different thing, you need to set your hive to fully pumped not gravity

 

[Mister Banks]

I'm sorry but I'm so confused. I presume I have a fully pumped gravity fed system then ?If it's a gravity system should I have left my Hive receiver on the blue setting for a gravity fed system. Someone said earlier it wasn't so I changed it.

It is confusing when you get conflicting responses. You have a pumped central heating system which can be either pressurised or open vented (some say this is gravity fed but it isnt). Your system is pumped and if you have a small tank in the loft feeding it then it is open vented but if no tank exists it is pressurised.