Cental heating nightmare - help me solve a 12 month problem!

[Agile]

A brave question T. . Any answers?


Am I due an email?

I sent you an email a few days ago but the one to blueyonder was returned but the other went somewhere! You need to put your preferred email on your profile as I do.

If two pumps were in series and one failed then they would both need to be taken out of service to repair.

In parallel one can be isolated and the system continues on one pump.

 

[Dan Robinson]

I haven't had a blueyonder address for 12 years or more.

My address is in my profile and website

 

[D_Hailsham]

It's not actually 'pumping' over. The vent and cold feed should be upstream of the pump.

It is upstream. You are assuming the pump is pumping upwards; it's not. (See OP's earlier reply.)

 

[Agile]

I haven't had a blueyonder address for 12 years or more.

My email system has a long memory! And I have been using the same addresses ever since email was marketed!

What about 101@gmail then?

 

[Dan Robinson]

That should be fine now I know something is coming,.

The one in my profile and website would be better though.

 

[VerticalTobe]

Just wanted to say thank you to everyone for their input - will be getting on to someone this week and the information you've given will come in handy.

It's interesting about boiler size and not running the CH and HW at the same time - when I bought the place they were on Economy 7, so probably running the HW at night when it was cheaper and (if they knew about the boiler being an issue) avoiding the problem.

Oddly I tried it today with the HW and CH on and the water in the F&E tank was cold. Switched off the HW and the water in the F&E started to warm.

I think whoever takes this one is going to have their work cut out!

 

[D_Hailsham]

It's interesting about boiler size and not running the CH and HW at the same time - when I bought the place they were on Economy 7, so probably running the HW at night when it was cheaper and (if they knew about the boiler being an issue) avoiding the problem.

Economy 7 is cheaper electricity at night. It will only be relevant if the hot water is heated by an electric immersion heater.

The suggestion to heat the cylinder overnight was made assuming it was being heated by the boiler.

Economy 7 is also useful for running dishwashers, washing machines & tumble driers overnight.

If the cylinder can be heated by the boiler, the immersion heater is provided as a backup, in case the boiler packs up.

 

[St0rmer66]

Typical install for a 38HXI from what I've seen! (was one of the cheapest high output heat only available). Can't remember the last time I saw one installed on a correctly designed system!

Bigger pump (25-80) absolutely necessary, or a second 15-60 in series for a cheaper option. Combine cold feed and open vent if it were me, having them in that "H" shape always causes problems in my experience (adding a more powerful pump will only exasperate it sucking air in etc). Auto bypass definitely needed, nothing to do with the power of the boiler (although more powerful makes it worse), it should have one regardless. Hopefully pump is wired to the boiler too, not the motorised valves, so that you have a pump overrun.

It may sound a lot but it's honestly not that bad of a job. You'll be amazed at the difference it makes to how much better it heats up after!

 

[Agile]

Why do you recommend the two pumps in series?

 

[St0rmer66]

Because it'll give between 11 and 12m of head. Single bigger pump is the better option.

 

[D_Hailsham]

You don't need a 12m head, and consequently a larger/second pump, if the system is balanced for the boiler's expected differential of 20C.

 

[St0rmer66]

You don't need a 12m head, and consequently a larger/second pump, if the system is balanced for the boiler's expected differential of 20C.

Assuming the OP is willing to mess around for the whole of winter trying to get every rad accurate to within an eighth of a turn on the lockshield valves to then find its gone back out next year anyway . Add to that slow heat up (17 rads is not small) and no provision for even the slightest of blockages. Bigger pump will help all round. Some systems simply cannot be at a 20C differential unless you start again with new rads and pipework.

 

[D_Hailsham]

You don't need a 12m head, and consequently a larger/second pump, if the system is balanced for the boiler's expected differential of 20C.

Assuming the OP is willing to mess around for the whole of winter trying to get every rad accurate to within an eighth of a turn on the lockshield valves to then find its gone back out next year anyway

Why should it take the whole winter to obtain an acceptable balance, and why should it go out?

Add to that slow heat up (17 rads is not small) and no provision for even the slightest of blockages.

Provided the rads are giving out the required amount of heat, why should the house heat up any slower?

Some systems simply cannot be at a 20C differential unless you start again with new rads and pipework.

I'm inclined to agree with that. I wonder how many installers are correctly sizing the pipes to take account of the lower flow rate, and consequently reduced head loss, for a new system designed with a 20C differential?