Unvented Cylinder, Central Heating and Underfloor Heating

[T786]

Hi,

I have a couple of problems with my heating system. I have a detached house in crosland moor, huddersfield that is approximately 3000 sq ft and is currently running on a 2014 Vaillant ecotec 28kw boiler.

The central heating system was a gravity fed system which was upgraded to a Unvented cylinder (400l) approximately 5 years ago. There are 2 emersion heaters in the tank and everytime I switch them both on, this trips the electrics however, if any one heater is switched on it does not trip but takes several hours to heat the tank.

The cold water pressure drops instantly as soon as more than one tap is opened. If you are having a shower and another tap is opened the pressure is reduced where the shower is literally trickling with water. There are 3 bathrooms, 2 toilets and 2 kitchens in the house. The mains pipe to stop tap is 25mm blue pipe, but then runs on a 15mm pipe to test of the house.

One room was renovated and was fitted with underfloor heating. The company connected the underfloor heating pipe which is a 100m 15mm to the existing radiator and installed a pump on this. Everytime the pump is turned to its maximum setting this room warms up, but the rest of the house is deprived with heat.

There are 11 radiators with the following sizes:

1200mm x 600mm double
1200 x 600 double
1200 x 450 single
1800 x 600 single
1450 x 450 double
1200 x 600 double
2200 x 450 double
2200 x 450 double
1000 x 450 double
1000 x 600 double
1300 x 450 double

Even with the underfloor heating pump turned to minimum there are radiators in the house which do not get warm. By turning off the hot radiators, I can get each one to heat up by itself, so I don't think it's sludge. I just can't get them all hot at the same time, no matter how I try and balance the system.

Any comments would be appreciated.

 

[oldbutnotdead]

Firstly, whoever installed your unvented needs slapping-15mm is never going to be adequate, shld be minimum 22mm all the way back to the MDPE.
Was the installer G3 certified? Has the system been annually maintained again by a G3 certified engineer? (This is important with pressurised cylinders)
The UFH install sounds like a massive lashup as well- take it there's a single loop, no manifold, no bypass? If you isolate the UFH entirely (are there valves after the thing is teed off the rad) does the rest of the house heat up properly?

 

[picasso]

It sounds like The pump in the boiler cannot cope with the rads and the ufh , I would recommend either close coupled tees or a low loss header.

 

[T786]

Thank you for the response. It was done through a builder, not sure on the qualifications side. It has not been maintained annually. Even with the UFH completely turned off all the rads do not heat up

 

[picasso]

Did it ever work properly ?

 

[T786]

No it never worked properly

 

[picasso]

What model of ecotec do you have have 428, 628 ect

 

[T786]

It is the ecotec 428

 

[picasso]

Try this... get the instruction manual for your boiler and find out how to get in to the D codes, when you have go to D0 and reduce the output to 24 and see if your rads heat any better, chances are that you will have to upgrade the pump regardless.

 

[flameport]

There are 2 emersion heaters in the tank and everytime I switch them both on, this trips the electrics however, if any one heater is switched on it does not trip

Most likely both wired to the same 16A circuit, rather than a single higher rated circuit or 2x circuits.
Even with both on, it would still be hours to heat a 400l cylinder.

Those heaters should be for backup only if the boiler fails - the boiler should be used to heat the cylinder as it will be much faster and considerably cheaper.

 

[T786]

I have not got the manual to look up the codes.

The water does heat with the boiler with no issues at all.

I have attached some photos of the pump and the cyclinder.

 

[picasso]

Can you post a pic of the front of the blue pump ? does this help ?

 

[T786]

Hi yes it does help, I will try that and let you know of the outcome

 

[T786]

 

[picasso]

Yea pumps not man enough for your system, once its overcome the resistance of the boiler heat exchanger there is not enough oomph to push the water against the pipework resistance, as I said earlier close coupled tees or a low loss header,