Converting a gravity HW system to fully pumped

[raymondo]

Hi all, I'd like some advice on the following;

I have a 10yo Halstead boiler and has gravity feed HW and pumped rads. Have a room stat that controls the pump and no stat on the HW cylinder.

This all works very well for our needs, we always need and use HW and the heating goes on and off via the room stat as required.

All the reading I do about this "old type" of system is that it's very inefficient so I'm wondering what savings will I make by changing to a fully pumped system ?

I know this is a bit of a "how long is a piece of string" question but wondering if anyone can give a % saving based on their own situation.

My current system is very simple and it's working well so do I need to fix what aint broke ?

Thanks in advance... Ray

ps. What started this off was I'm looking at a DIY solar installation and was checking out the new HW cylinder connections etc !

 

[migoplumber]

the new boilers are very effiecient. some claim to be 106% effiecent, i still havnt got my hear round that, but will one day!!
your old boiler could still be running at 95% or more?
in your yearly safety test, that i hope you have! the flue gas analysis will tell you your boiler effiecency.
one way of explaing it in laymans terms is.
gas bill 100 quid, 100% effiecent equals 100 quids worth of heat going into your house.
gas bill 100 quid, 85% effiecent equals 8 quids worth of heat into your house and 15 quid in rubbish bin.
if your bill over the year is 2000 quid@ 85% effiecency equal throwing away 300 quid a year!!
after 3 years you have paid for a new better boiler, and start ro save money, and enviroment!
if you know include a new unvented cylinder, with your diy solar panels you could halve your bill during winter and have free hot water in summer SO LONG as your panels are installed correctly and commisioned well.

good luck
shaun

the maths isnt quite that simple. but im trying to keep it that way!!

 

[raymondo]

Thanks for the feedback Shaun.

Anyone else with anything to add ?

Cheers... Ray

 

[leakylea]

stick with what you have, a new system complete with quality goods is a couple of grand minimum, it will take years for you to save that much on a new boiler etc put a few quid away every month and you'll have a war fund when the boiler gives up, a good service will more than pay for itself efficiency is the way to go but throwing money away is not

 

[feltham]

the new boilers are very effiecient. some claim to be 106% effiecent, i still havnt got my hear round that, but will one day!!

migoplumber you said some are 106% effiecent dos ethat mean you get a rebate when you bill comes round? i cant get my head round that either so your not alone
dont most boilers now claim to be 90-95% effiecent ?
can you ever make a boiler run 100% effiecent?

 

[raymondo]

Thanks Guys

Just to confirm what I'm on about here... I'm not wanting to replace my boiler. I was looking into changing the existing setup from gravity to fully pumped and trying to get a feel for what the benefits will be.

Thanks... Ray

 

[migoplumber]

feltham, i read that a couple of weeks back 106% effiecent boilers, thats why it stuck in my brain.
dosnt mean its true tho.
i have been reading through all my mags and cant find it now. promise you i read it, and when i find it ( i will ) i shall post it.!!

shaun

 

[Mike Jackson]

It's all to do with how you measure efficiency. Gross or Nett.

Mike

 

[Bernie2]

One of the things about pumped hot water as against gravity is that the cylinder recovery times are shortened tremendously. That in itself is worth a few bob just in convenience alone.

As to the exact savings you would make, that can be a bit difficult to say, it depends on so many factors.
If you have a gravity system that takes longer to heat up, then the heat losses from the primary pipework are bound to be greater, simply because the hot water is in the pipework longer and so it gives the heat a longer time to escape.

Also a gravity system being slower to circulate tends to keep the boiler going longer as the primary return temperature is lower. Whereas the pumped system whilst doing the same would return hot water back to the boiler quicker and so shut the boiler off sooner saving fuel.

On balance, if its an easy job, do it, if not have a cup of tea and change it if the boiler or cylinder breaks down.