Central heating problems

[Gaz the Sparky]

Hi I could do with peoples input into how my heating system has been plumbed.

I have a problem where there are 2 radiators in the front room of the house that heat up fine when just the heating is on but as soon as the hot water goes on too it makes the these 2 radiators go cold.

I have balanced all the radiators in the house by closing all the lockshields down and opening the downstairs ones a quarter of a turn and the upstairs ones until the radiator gets warm.

I think that when there is demand for the hot water and the zone valve opens it bypasses the flow and means that the water takes the easiest route back to the boiler.

i have attached a picture of the pipework layout to see if you can see any problems.

I have several questions regarding the plumbing but need to try and get this one resolved first

pipework from left to right

Boiler flow
Boiler Return
Radiator flow
Radiator Return
Hotter out
Cold water supply

cheers

 

[rochdalegas]

I think a good starting point would be to fit a gate valve on the hot water side so that can be balanced down along with the radiators. Above to motorized valve on the hw flow

 

[Gaz the Sparky]

Thanks for the reply.
So does that look like a standard piping layout? If I install a gate valve just after the zone valve before it goes into the tank that should slow the flow down so it doesn’t starve the randiators.

My thoughts are that the way that they have piped the hw zone valve it means the flow takes a easier route going straight through the T piece rather than 90degrees to the radiator zone valve could that be the issue?

I am adding another heating zone and then also a bypass valve so think I’m going to have to remove the above pipework and install it all again to get The best layout.

How best would it be to pipe it up correctly.

Should it be flow from the boiler to a 3 separate Tees one to each zone valve then from the last Tee to the bypass valve and back to the boiler return

Next thing is they have installed the expansion vessel Teed off the 22mm hot water outlet at the top of the tank

Is this correct? I have always seen the expansion vessel to be plumbed off of the mains inlet pressure regulator.

They haven’t installed a balanced cold water feed off of the regulator either they have just installed and capped a 22mm pipe

I am installing 2 thermostatic showers so think I need to install a balanced cold feed for these.

I have followed the cold pipework and it comes in under the sink in the kitchen up to under the floor and tees off to the 2 bathrooms and then again to the 22mm feed in the airing cupboard. I guess that I should take bathrooms off of this and put the cold feed direct to the airing cupboard and then a balanced feed from the valve back to the bathroom feeds.

Should I do this for everything in bathrooms or is it best to keep the toilets and the sinks and bath taps on the mains and just the shower feeds on this balanced feed ?

Thanks for any advice

 

[rochdalegas]

Firstly ive never held my g3 cert so im unqualified to advise on position of expansion etc im sure there are more experienced who would be more knowledgable. You should
also get someone in to to that side with appropiate quals. As for the heating side. Its worth checking if your boiler has an intetnal bypass before fitting one. Water always take the route of least resistance but correctly balanced it should work fine no matter what positions the valves are in have you considered something like evohome instead of seperate zoned heating areas as it means no messing with re routing pipework.

 

[DP]

I think a good starting point would be to fit a gate valve on the hot water side so that can be balanced down along with the radiators. Above to motorized valve on the hw flow

Or heat water when ch is not required, like at 2.00 am or similar time

 

[Gaz the Sparky]

Or heat water when ch is not required, like at 2.00 am or similar time

thanks i would like to fix the problem rather than just heat the water at night. I am fitting a big bath which will drain the tank so want the option to have both on at the same time

 

[DP]

You do realise if the cylinder is cold, it will need some 24kw of energy which will reduce as HW temperature starts to rise towards target temperature. These cylinders are designed to reach 75% capacity in 15 or 20 minutes.

You could always rate the cylinder coil to 3kw as one regular here was constantly advocating which then allows you to have two or three zones running in tandem but you can forget the rapid reheat that these cylinders are capable of. By the way, I would like to see you achieve 20 degree differential when cylinder cold

Option is either fit a boiler that will allow heating to be, say 18kw if biggish house and say 20kw for cylinder, needing a boiler of 38kw output.
OR a 24kw boiler that does the job amicably as suggeste above.

Boiler heats the cylinder to full capacity when heating not required, you fill your uber big bath with lovely hot water when you feel like it and then defer the HW heating to possibly be dialysed a little till heating goes off

There are other ways to deal with thus situation using smart controls.

 

[Wildcat1961]

Thanks for the reply.
So does that look like a standard piping layout? If I install a gate valve just after the zone valve before it goes into the tank that should slow the flow down so it doesn’t starve the randiators.

My thoughts are that the way that they have piped the hw zone valve it means the flow takes a easier route going straight through the T piece rather than 90degrees to the radiator zone valve could that be the issue?

I am adding another heating zone and then also a bypass valve so think I’m going to have to remove the above pipework and install it all again to get The best layout.

How best would it be to pipe it up correctly.

Should it be flow from the boiler to a 3 separate Tees one to each zone valve then from the last Tee to the bypass valve and back to the boiler return

Next thing is they have installed the expansion vessel Teed off the 22mm hot water outlet at the top of the tank

Is this correct? I have always seen the expansion vessel to be plumbed off of the mains inlet pressure regulator.

They haven’t installed a balanced cold water feed off of the regulator either they have just installed and capped a 22mm pipe

I am installing 2 thermostatic showers so think I need to install a balanced cold feed for these.

I have followed the cold pipework and it comes in under the sink in the kitchen up to under the floor and tees off to the 2 bathrooms and then again to the 22mm feed in the airing cupboard. I guess that I should take bathrooms off of this and put the cold feed direct to the airing cupboard and then a balanced feed from the valve back to the bathroom feeds.

Should I do this for everything in bathrooms or is it best to keep the toilets and the sinks and bath taps on the mains and just the shower feeds on this balanced feed ?

Thanks for any advice

Seek the advice of a G3 registered engineer.
You fail to mention type of boiler/pump.

 

[Gaz the Sparky]

Thanks all for the replies

I had problems with the company who installed the system and have lost all confidence in how they have installed the system. I have a nest thermostat installed onto the system and this is working well. Its just that when the nest is programmed to heat the hot water for 2 hours in the evening the 2 radiators go cold. The company said that the heating needed to be balanced but they didn't come back to do that. I have balanced all the radiators and all get hot and are fine when just the heating on. When the water kicks in the 2 radiators go cold.

I understand that if its a cold tank of water then it will take a lot of heat to heat the water.

The boiler is a system boiler 30kw with the pump integral, brand new and new tank the only old thing was the radiators and the pipework. They didn't power flush the system and the bottoms of the radiators were cold so I have had to remove all the radiators and flush them through and have had to clean the magnaclean once a week as its picking up loads of metal fillings. I am on my second treatment bottle of cleaner I have left both treatments in for 4 weeks to work its way through.

I think as you say its best to pay another G3 Registered engineer to come out and check over my install and put my mind at rest.