HW and CW Slow To Reach Good Temp

[Bigfoott]

Hi,

I've just had all my radiators replaced and moved from internal walls to outside walls, most of the single panel rads were replaced with double panel, by making them double I was effectively adding 6 new single panel 600mm x 1600mm rads to they system. The boiler an Ideal Classic max BTU output is about the same as the total radiators output so should cope.

Since the moving and adding of new rads i've noticed that its taking alot longer for my CH and HW to reach a usual temp. both the HW and CH come on at 6:30am, I'm in the shower at 7am and before it used to be really hot, now its luke warm at best. If I leave it an hour its fine its hot enough.

Could the fact that the CH has to move the water around alot more now, and boiler needs to do more work due to double panel rads and longer pipes result in the water taking longer to get around the system and heat ? Ive checked the thermostat the boiler one, main room one and water one and there all as they were, the pump is at max setting as well.

 

[JohnD]

if you've doubled the amount of water and metal in the heating system, it will take the boiler longer to heat them all up. But they will stay hot for longer. My rads contain about 100 litres of water which is about the same as a cylinder, I don't know how much heat all that steel absorbs, the boiler should be able to get either of them hot within 20-30 minutes, but perhaps not both unless it is a pretty big one.

Bringing the system from cold to hot wil take more power than maintaining them at hot. Imagine boiling an iron pan of water; once it's hot you turn the gas down to keep it simmering.

Is your cylinder cold overnight? A well insulated cylinder will easily stay hot enough for a bath for 24 hours. So are you either draining all the hot out with a long bath after the boiler has shut down the previous evening, or is the cylinder not properly insulated?

 

[Bigfoott]

Thanks for the reply, Cylinder doesnt havent an insulation jacket on but it looks new so it should have one built in. They were up in the loft water tank up there that has insulation on will see if its come off.

I will keep an eye on it but it probably is due to the fact there is more rads and further for the water to get around. Plumber did mention I could do with a power flush at some point but to first 'see how it goes'.

I had a look under the floor board to check his handy work out, to extend the piping to the new rad location he used what looks like grey rubber hose and only used copper pipe at the end where it came up through floor board for the value, is it usual to use hose these days instead of copper pipe ?

 

[Diyisfun]

Have the water come on before the heating OR at night let the water remain on after the heating has gone off. 30 minutes is all you need.

 

[JohnD]

Thanks for the reply, Cylinder doesnt havent an insulation jacket on but it looks new so it should have one built in.

modern cylinders are encased in green/blue rigid plastic foam insulation. If yours has this it is OK (I put a red fibreglass jacket over mine as well because I had it spare). If you can see any bare copper it must be insulated.

all pipes in unheated areas like lofts must have the thick plastic foam insulation (Climaflex or similar) which looks as thick as your arm (a cheaper, thinner version can be used inside the house) it is an easy DIY job to fit

plastic pipe is OK (it should be fairly hard, not like hosepipe!)

you can give the system a chemical clean yourself, it is pretty easy if you have a feed & expansion tank in the loft and can find a drain-off downstairs (£30 in chemicals and a couple of sessions work) and keeping it clean and inhibited can save you hundreds on a powerflush or repairs later if it gets blocked.

 

[bengasman]

Hi,


Since the moving and adding of new rads i've noticed that its taking alot longer for my CH and HW to reach a usual temp. both the HW and CH come on at 6:30am, I'm in the shower at 7am and before it used to be really hot, now its luke warm at best. If I leave it an hour its fine its hot enough.

The whole idea of having a 2-channel programmer is to be able to have heating demand separated from dhw demand. Cylinders can take the same amount of heat as half a dozen rads, so if you run the cyl at different times from the heating, they will both be a lot quicker to respond

 

[Bigfoott]

Hi thanks for the advice . Ive got one of these timers http://content.honeywell.com/uk/homes/Technical/STX99/st799user.pdf doesnt look like I can control the hw and ch seperately, will have to look into that.

 

[JohnD]

have you checked the cylinder insulation?

 

[bengasman]

you can replace it with st 6400, should even be the same back plate. you may have to swap 2 wires, can not remember, but is straight forward job